Umarh bint 'Abdur Rahman عمرة بنت عبد الرحمن بن سعد بن زرارة · Fasting (Kitab Al-Siyam)

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).

The Prophet (ﷺ) used to observe I'tikaf during ten days of Ramadan every year. But when the year in which he died, he observed I'tikaf for twenty days.