Sunan Abi Dawud Fasting (Kitab Al-Siyam) Aban bin Salah bin 'Umayr أبان بن صالح بن عمير Amr bin Muhammad al-Anqazi عمرو بن محمد العنقزي Sahih Umar (may Allah be pleased with him) took a vow in the pre-Islamic days to spend a night or a day in devotion near the Ka’bah (in the sacred mosque). He asked the Prophet (ﷺ) about it. He said: Observe i’tikaf (i.e. spend a night or a day near the Ka’bah) and fast. https://parallelquran.com/hadith/sunan-abi-dawud-2474/