1381 — Musa ibn Isma'il narrated to us, Wahib narrated to us, Ayyub narrated to us, from 'Ikrimah, from Ibn 'Abbas, from the Prophet, peace and blessings be upon him, who said: "Seek it in the last ten nights of Ramadan: in the ninth night that remains, in the seventh night that remains, and in the fifth night that remains."(1)

318 — Chapter: On those who said: The night of the twenty-first

1382 — Al-Qa'nabi narrated to us, from Malik, from Yazid ibn 'Abdullah ibn al-Had, from Muhammad ibn Ibrahim ibn al-Harith al-Taymi, from Abu Salamah ibn 'Abd al-Rahman, from Abu Sa'id al-Khudri, who said: The Messenger of Allah, peace and blessings be upon him, used to observe i'tikaf during the middle ten days of Ramadan. He observed i'tikaf one year until, when the night of the twenty-first came — which was the night on which he would emerge from his i'tikaf — he said: "Whoever has been observing i'tikaf with me, let him observe i'tikaf during the last ten nights. I was shown this night, then I was made to forget it. And I saw myself prostrating on the morning of that night in water and mud. So seek it in the last ten nights, and seek it in every odd night."(2)

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(1) Its chain of transmission is authentic. Wahib: he is Ibn Khalid, and Ayyub: he is al-Sakhtiyani.
Al-Bukhari also narrated it (2021) from Musa ibn Isma'il, with this chain of transmission.
Al-Bukhari also narrated it (2022) via the path of 'Asim al-Ahwal, from Abu Mijlaz and 'Ikrimah, from Ibn 'Abbas, with similar wording.
It is also in "Musnad Ahmad" (2052).

(2) Its chain of transmission is authentic. Al-Qa'nabi: he is 'Abdullah ibn Maslamah.
It is with Malik in "Al-Muwatta'" 1/319, and from his path al-Bukhari narrated it (2027), and al-Nasa'i in "Al-Kubra" (686) in abbreviated form, and (3373).
Al-Bukhari also narrated it (2018), Muslim (1167), al-Nasa'i (1281) and he has (3328) via two paths from Muhammad ibn Ibrahim, with the same wording. =