It was narrated from ‘Umar that he had vowed during the days of Ignorance to spend one night in I’tikaf. He asked the Prophet (ﷺ) about it, so he commanded him to spend it in I’tikaf.
Hadith Referenceسنن ابن ماجه / كتاب الصيام / 1772
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:بخاري ومسلم