Hadith No: 1
Ahmad ibn Hanbal - Musnad al-Imam Ahmad ibn Hanbal
Remaining Musnad of the Major Pretenders - Musnad of Abu Huraira (r)
Volume: (2) - Page Number: (441)
9395 - Muhammad ibn Ubayd al-Tanufasi narrated to us, who said: Yazid ibn Kaysan narrated to us, from Abu Hazim, from Abu Huraira, who said: The Prophet (peace be upon him and his holy progeny) visited his mother's grave and wept, and those around him wept as well. Then the Messenger of Allah (peace be upon him and his holy progeny) said: "I asked my Lord for permission to pray for her forgiveness, but I was not given permission. I asked Him for permission to visit her grave, and He granted me permission. So visit graves, for they remind you of death."

---

Reference: Musnad Ahmad Ibn Hanbal Book 2

Hadith No: 2
Ahmad ibn Hanbal - Musnad al-Imam Ahmad ibn Hanbal
Remaining Musnad of the Excessive Narrators - Musnad of Abu Huraira (r)
Volume: (2) - Page Number: (527)
10434 - Abdullah ibn Yazid narrated to us, saying: Hiyuwa narrated to us, saying: Abu Sakhr narrated to us that Yazid ibn Abdullah ibn Qusayt informed him from Abu Huraira, from the Messenger of Allah (peace be upon him and his holy progeny), who said: "There is no one who greets me with peace except that Allah, the Almighty, returns my spirit to me so that I can return the greeting."

---

Reference: Musnad Ahmad Ibn Hanbal Book 2

Hadith No: 3
Ahmad ibn Hanbal - Musnad al-Imam Ahmad ibn Hanbal - Musnad Abi Sa'id al-Khudri (ra)
Volume: (3) - Page Number: (38)
10936 - Yahya ibn Adam narrated to us, who said: Ibn Mubarak narrated to us, from Usamah, from Muhammad ibn Yahya ibn Hibban, from his uncle, from Abi Sa'id al-Khudri, who said: The Messenger of Allah (peace be upon him and his holy progeny) said: "I had prohibited you from visiting graves, but now visit them," for they contain lessons. And I had prohibited you from drinking nabidh, but drink it, and nothing intoxicating is made permissible. And I had prohibited you from sacrifices, but eat (from them)."

---

Reference: Musnad Ahmad Ibn Hanbal Book 3

Hadith No: 4
Ahmad ibn Hanbal - Musnad al-Imam Ahmad ibn Hanbal
Remaining Musnad of the Ansar - Hadith of Abu Ayyub al-Ansari (r)
Volume: (5) - Page Number: (422)
23074 - Abd al-Malik ibn Amr narrated to us, who said: Kathir ibn Zayd narrated to us, from Dawud ibn Abi Salih, who said: "Marwan approached one day and found a man with his face on the grave. He said: 'Do you know what you are doing?' He then leaned closer, and it was Abu Ayyub. Marwan said: 'Yes, I came to the Messenger of Allah (peace be upon him and his holy progeny) and did not come to the stone.'" I heard the Messenger of Allah (peace be upon him and his holy progeny) say: "Do not weep for the religion when its people take charge of it, but weep for it when those not of its people take charge of it."

---

Reference: Musnad Ahmad Ibn Hanbal Book 5