When is I'tikaaf? (Hadith No. 1751)

Hadith no. 1749 and 1750 (below) are repeats. Read the post here.
Volume 3, Book 33, Number 254:
Narrated 'Ali bin Al-Husain (from Safiya, the Prophet's wife):
The wives of the Prophet (sallallaahu `alayhi wasallam) were with him in the mosque (while he was in Itikaf) and then they departed and the Prophet (sallallaahu `alayhi wasallam) said to Safiya bint Huyai (radiallaahu `anhaa), "Don't hurry up, for I shall accompany you," (and her dwelling was in the house of Usama). The Prophet (sallallaahu `alayhi wasallam) went out and in the meantime two Ansari men met him and they looked at the Prophet (sallallaahu `alayhi wasallam) and passed by. The Prophet (sallallaahu `alayhi wasallam) said to them, "Come here. She is (my wife) Safiya bint Huyai." They replied, "Subhan Allah, (How dare we think of evil) O Allah's Apostle (sallallaahu `alayhi wasallam)! (we never expect anything bad from you)." The Prophet (sallallaahu `alayhi wasallam) replied, "Satan circulates in the human being as blood circulates in the body, and I was afraid lest Satan might insert an evil thought in your minds."

Volume 3, Book 33, Number 255:
Narrated 'Ali bin Al-Husain from Safiya (radiallaahu `anhaa):
Safiya (radiallaahu `anhaa) went to the Prophet (sallallaahu `alayhi wasallam) while he was in Itikaf. When she returned, the Prophet (sallallaahu `alayhi wasallam) accompanied her walking. An Ansari man saw him. When the Prophet (sallallaahu `alayhi wasallam) noticed him, he called him and said, "Come here. She is Safiya (radiallaahu `anhaa). (Sufyan a sub-narrator perhaps said that the Prophet (sallallaahu `alayhi wasallam) had said, "This is Safiya"). And Satan circulates in the body of Adam's offspring as his blood circulates in it."
(A sub-narrator asked Sufyan, "Did Safiya (radiallaahu `anhaa) visit him at night?" He said, "Of course, at night.")

Today's Hadith:

Volume 3, Book 33, Number 256:
Narrated Abu Said (radiallaahu `anhu):
We practiced Itikaf with Allah's Apostle (sallallaahu `alayhi wasallam) in the middle ten days (of Ramadan). In the morning of the twentieth (of Ramadan) we shifted our baggage, but Allah's Apostle (sallallaahu `alayhi wasallam) came to us and said, "Whoever was Itikaf should return to his place of Itikaf, for I saw (i.e. was informed about the date of) this Night (of Qadr) and saw myself prostrating in mud and water." When I returned to my place the sky was overcast with clouds and it rained. By Him Who sent Muhammad (sallallaahu `alayhi wasallam) with the Truth, the sky was covered with clouds from the end of that day, and the mosque which was roofed with leaf-stalks of date palm trees (leaked with rain) and I saw the trace of mud and water over the nose of the Prophet (sallallaahu `alayhi wasallam) and its tip.
This Hadith explains this one narrated by Abu Hurairah (radiallaahu `anhu):
"The Messenger of Allaah (peace and blessings of Allaah be upon him) used to observe i’tikaaf for ten days every Ramadaan, and in the year in which he passed away he observed i’tikaaf for twenty days." Narrated by al-Bukhaari.
And this is why I`tikaaf in the last ten days of Ramadaan is more recommended than any other time.. Prophet (sallallaahu `alayhi wasallam) preferred it in his last year.
But this doesn't mean one can't observe I`tikaaf in days other than the last ten of Ramadaan. I`tikaaf can be practiced any time of the year. Read this post for more details.