Sunan Abi Dawud Book 14, Hadith 150

The Prophet (ﷺ) used to observe retirement (i'tikaf) to the mosque during the last ten days of Ramadan till Allah took him, and then his wives observed retirement to the mosque after his death.

Previous Hadith

When one of you is invited (to a meal), and he is fasting, he should say that he is fasting.

Sunan Abi Dawud Book 14, Hadith 149
Next Hadith

The Prophet (ﷺ) used to observe i'tikaf during the last ten days of Ramadan. One year he did not observe i'tikaf. When the next year came, he observed i'tikaf for twenty nights (i.e. days).

Sunan Abi Dawud Book 14, Hadith 151