Here are some Hadiths regarding "visiting the graves or shrines". I will not comment anything, I just want to present the Ahadith. Some say "there's nothing in the grave" and "visiting the grave is a shirk". In fact, visiting simply the graves is not a shirk. Some members were even speaking about demolishing the graves and shrines.
1. “Whoever visits my grave after my death is as those who visited me in my life.”
Narrated by al-Tabarānī in al-Kabīr (12:406) and al-Awsat. (1:94) with a chain containing ‘Ā’isha bint Yūnus, whose status is uncertain, and from H. āt.
ib by al-Dāraqutnī (2:278) with another chain which al-Dhahabī said
was one of the best chains in that chapter.
“Whoever makes pilgrimage then visits me after my death it is as if he visited me in my life.”
Narrated by al-T. abarānī in al-Kabīr (12:406), al-Dāraqut.nī (2:278), and al-Bayhaqī, Sunan, (5:246#10054-10055)all through H.afs. ibn Abī Dāwūd al-Qārī whom only Ahmad declared passable (sālih).
1. "Allah has defended the earth from consuming the bodies of Prophets".
A sound (sahih) tradition related on the authority of Aws ibn Aws al-Thaqafi by: Ahmad in his Musnad, Ibn Abi Shaybah in the Musannaf, Abu Dawud in the Sunan, Nisa'i in his Sunan, Ibn Majah in his Sunan, Darimi in his Musnad, Ibn Khuzaymah in his Sahih, ibn Hibban in his Sahih, Hakim in the Mustadrak, Tabarani in his Kabir, Bayhaqi in Hayat al-anbiya', Suyuti in Anba' al-adkhiya, Dhahabi who confirmed Hâkim's grading, and Nawawi in the Adhkar.
Another version in Ibn Maja has this addition:
"And the Prophet of Allah is alive and provided for."
Bayhaqi mentions it also in the Sunan al-kubra.
2. "The Prophets are alive in their graves, praying to their Lord".
A sound (sahih) tradition related on the authority of Anas ibn Malik (r) by: al-Bazzar in his Musnad, Abu Ya`la in his Musnad, Ibn `Adi in al-Kamil fi al-du`afa', Tammam al-Razi in al-Fawa'id, al-Bayhaqi in Hayat al-anbiya' fi quburihim, Abu Nu`aym in Akhbar Asbahan, Ibn `Asakir in Târeekh Dimashq, al-Haythami in Majma` al-zawa'id (8:211), al-Suyuti in Anbâ' al-adhkiya' bi-hayat al-anbiya' (#5), and al-Albani, in Silsilat al-ahadith al-sahihah (#621).
3. "No-one greets me except Allah has returned my soul to me so that I can return his salâm".
From Abu Hurayra, in Abu Dawud with a sound (SaHeeH) chain. This hadith has been adduced by the scholars as the legal proof for the validity and modality of visiting and greeting the Prophet , although the hadith does not mention the necessity of physically visiting the Prophet in Madina.
A note about the translation of "has returned": Suyuti said that "radda" means `ala al-dawâm," i.e. permanently, and not temporarily: in other words, Allah does not return the rûH and take it back, then return it again and then take it back again, but He returned it to the Prophet permanently, and the Prophet is alive permanently.
Sakhawi, Ibn Hajar al-`Asqalâni's student, said: "As for us (Muslims) we believe and we confirm that he is alive and provided for IN HIS GRAVE" (al-qawl al-badee` p. 161). Ibn al-Qayyim said in al-RûH p. 58: "It is obligatory knowledge to know that his body is in the earth tender and humid (i.e. as in life), and when the Companions asked him: 'How is our greeting presented to you after you have turned to dust' he replied:
'Allah has defended the earth from consuming the flesh of Prophets,'
and if his body was not in his grave he would not have given this answer."
4. "Whoever invokes blessings on me at my grave, I hear him, and whoever invokes blessings on me from afar, I am informed about it."
Ibn Hajar says in FatH al-Bâri 6:379: "Abu al-Shaykh cites it with a good chain (sanad jayyid)," and Bayhaqi mentions it in Hayât al-anbiyâ with "ublightuhu" in the end.
5. "Whoever visits my grave, it becomes incumbent upon me to intercede for him."
Narrated by al-Daraqutni, al-Dulabi, al-Bayhaqi, Khatib al-Baghdadi, al-`Uqayli, Ibn `Adiy, Tabarani, and Ibn Khuzaymah in his Sahih, all through various chains going back to Musa ibn Hilal al-`Abdiyy from Ubayd Allah Ibn Umar, both from Nafi`, from Ibn `Umar.
Dhahabi declared this chain hasan (fair) as narrated, in "Mizan al- i`tidal," vol. 4, p. 226: "Huwa salih al-hadith" which means:"He -- Musa ibn Hilal -- is good in his narrations." Al-Sakhawi confirmed him in the "Maqasid al-hasana", while al-Subki declared it sahih according to Samhudi in Sa`adat al-dârayn 1:77. Ibn `Adiyy said: "He [Musa ibn Hilal] is most likely acceptable; other people have called him 'unknown' and this is not true... He is one of the shuyukhs of Imam Ahmad and most of them are trustworthy." al-Kamil fi al-Du`afa (6:2350). Albani declared him "thabit al-riwaya" (of established reliability) in his Irwa' 4:338. About `Ubayd Allah ibn `Umar al-`Umari: - Dhahabi calls him "saduq hasan al-hadith" [truthful, of fair narrations] al-Mughni 1:348; - Sakhawi says of him "salih al-hadith" [of sound narrations] al-tuhfat al-latifat 3:366; - Ibn Mu`in said to Darimi about him: "salih thiqat" [sound and reliable] al-kamil 4:1459.
6. The Prophet said: "I forbade you to visit the graves but [now] do visit them!"
Narrated as part of a longer hadith: from Burayda by Muslim, al-Tirmidhi (hasan sahîh), Abu Dawud, al-Nasa'i, `Abd al-Razzaq (3:569), and others; from Abu Sa`id al-Khudri by Ahmad with a chain of sound narrators as stated by al-Haythami (3:58), Malik, al-Hakim (1990 ed. 1:530) who declared it sound by Muslim's criterion, al-Bayhaqi in al-Sunan al-Kubra (4:77 #6984), and al-Bazzar with a chain of sound narrators as stated by al-Haythami (3:58); from Ibn Mas`ud by Ibn Majah, al-Daraqutni in his Sunan (4:259), `Abd al-Razzaq (3:572-573), Ibn Hibban (3:261), al-Hakim (1990 ed. 1:531), and al-Bayhaqi in al-Sunan al-Kubra (4:77 #6983) all with weak chains according to al-Arna'ut; from Anas by Ahmad and al-Bazzar with chains containing al-Harith ibn Nabhan who is weak according to al-Haythami (4:27), al-Hakim (1990 ed. 1:531-532), and al-Bayhaqi in al-Sunan al-Kubra (4:77 #6984)
7. `A'isha - Allah be well-pleased with her - said: "The Prophet forbade the visitation of graves then permitted it, and I think he said: `For, truly, they remind you of the hereafter.'"
Narrated by al-Bazzar with a chain of trustworthy narrators as stated by al-Haythami (3:58).
8. `A'isha asked: "What should I say, O Messenger of Allah [at al-Baqi`]?" He replied: "Say: `Greeting to you, O people of the abodes among the men and women believers! May Allah grant mercy to those of you and us who went ahead and those who tarried back! Truly we shall - if Allah wills - join up with you.'"
Al-Bayhaqi, al-Sunan al-Kubra (4:78), Ibn Hajar, Fath al-Bari (1959 ed. 3:184); al-Nawawi, Sharh Sahih Muslim (7:41-42)
9. The Prophet said: "I had forbidden you to visit the graves but Muhammad has been permitted to visit the grave of his mother, so visit them, for truly, they remind you of the hereafter."
Narated from Burayda by al-Tirmidhi (hasan sahîh). Also confirmed by Ahmad, ibn Majah and al-Nisai.
10. Another version states: "I forbade you to visit the graves then it appeared to me that they soften the heart, bring tears to the eyes, and remind one of the hereafter. Therefore, visit them, but do not say reprehensible things!"
Part of a longer hadith narrated from Anas by Ahmad.
STORIES OF SAHABIS AND PROPHET MOHAMMAD (PBUH)
11. Prophet placed a rock on top of `Uthman ibn Maz`un's (ra) grave saying: "With it I shall designate the grave of my [milk-]brother and later bury in it whoever dies among my relatives."
The hadith is narrated from an unnamed Companion by Abu Dawud and al-Bayhaqi in al-Kubra (3:412) with fair chains cf. Ibn Hajar, Talkhis al-Habir (2:134); Ibn al-Mulaqqin, Tuhfat al-Muhtaj (2:29). The complete report states that the Prophet asked a man to place a rock on top of Ibn Maz`un's grave; when he was unable to move it, he rolled up his sleeves and helped him and the whiteness of his arms was visible. Ibn Maz`un was the first of the Muhâjirûn buried in Baqi` al-Gharqad. Ibrahim, the Prophet's son, was buried next to him.
12. Dawud ibn Salih says: "[The Umayyad Caliph] Marwan [ibn al-Hakam] one day saw a man placing his face on top of the grave of the Prophet . He said: "Do you know what you are doing?" When he came near him, he realized it was Abu Ayyub al-Ansari. The latter said: "Yes; I came to the Prophet , not to a stone. I heard the Prophet say:
Do not weep on religion if its people assume its leadership (walyahu), but weep on it if other than its people assume it."
Ahmad 5:422, Hakim (Mustadrak 4:515); both the latter and al-Dhahabi said it was sahih. It is thus cited by as-Subki (Shifa' as-siqam p. 126), Ibn Taymiyya (al-Muntaqa 2:261f.), and al-Haythami (al-Zawa'id 4:2).
13. Imam Muslim relates in his Sahih, in the first chapter of the book of clothing, that Asma' bint Abi Bakr said: "Here is the cloak (jubba) of Allah's Messenger... [which] was with `A'isha until she died, then I got possession of it. The Apostle of Allah used to wear it, and we washed it for the sick so that they could seek cure thereby." Al-Nawawi comments in Sharh sahih Muslim (Book 37 Chapter 2 #10): "In this hadith is a proof that it is recommended to seek blessings through the relics of the righteous and their clothes (wa fi hadha al-hadith dalil `ala istihbab al-tabarruk bi aathaar al-salihin wa thiyabihim)."
14. Al-Bukhari narrates in his Sahih, Book of Jana'iz:
When `Umar was stabbed he sent his son `Abd Allah with a message to `A'isha to "Ask her if I can be buried with my two companions," that is, in her room, next to the Prophet and Abu Bakr. `A'isha replied: "I wanted the spot for myself, but I shall put him [`Umar] before me today." It had been her habit that if a man from among the Companions asked her that spot she would always refuse. She herself gave the following instructions before her death: "Bury me with my lady-friends (the wives of the Prophet MHMD in al-Baqi`) and do not bury me with the Prophet in the house, for I dislike to be held in reverence (inni akrahu an uzakka)." Ibn `Umar came back with the news, whereupon `Umar said: "NOTHING IN THE WORLD WAS MORE IMPORTANT TO ME THAN THAT RESTING-PLACE." Narrated by al-Bukhari in his Sahih.
15. `A'isha came to Mecca after her brother's death saying, "Where is the grave of my brother?" Then she came to the grave and prayed over him, a month after his death.7 Another version states that Ibn Abi Mulayka said: "`A'isha's brother died six miles away from Makka, so we carried him until we reached Makka and buried him there. `A'isha came to us after that and reproached us for doing so. Then she said: 'Where is the grave of my brother?' We showed it to her and she alighted in her howdah and prayed at his grave."
Narrated by `Abd al-Razzaq (3:518) and Ibn `Abd al-Barr in al-Tamhid (6:261)
16. Imam Ja`far al-Sadiq narrated with his chain from al-Hasan ibn `Ali that Fatima the daughter of the Prophet - may Allah be well-pleased with all of them! - used to visit the grave of her uncle Hamza ibn `Abd al-Muttalib every Jumu`a 21 and she used to pray and weep there.22 Another version adds that she had marked the grave with a rock in order to recognize it.
Al-Athram and Ibn `Abd al-Barr narrated it as mentioned by al-Qurtubi in his Tafsir (10:381); also `Abd al-Razzaq (3:574) with a very weak chain because of al-Asbagh ibn Nubata, who is discarded (matrûk) as a narrator.