Allah's Apostle used to practice Itikaf every year in the month of ...

Hadith 3:257

Narrated 'Amra bint 'Abdur-Rahman from 'Aisha:

Allah's Apostle used to practice Itikaf every year in the month of Ramadan. And after offering the morning prayer, he used to enter the place of his Itikaf. 'Aisha asked his permission to let her practice Itikaf and he allowed her, and so she pitched a tent in the mosque. When Hafsa heard of that, she also pitched a tent (for herself), and when Zainab heard of that, she too pitched another tent. When, in the morning, Allah's Apostle had finished the morning prayer, he saw four tents and asked, "What is this?" He was informed about it. He then said, "What made them do this? Is it righteousness? Remove the tents, for I do not want to see them." So, the tents were removed. The Prophet did not perform Itikaf that year in the month of Ramadan, but did it in the last ten days of Shawwal.