Sayyidah Safiyyah (may Allah be pleased with her) narrates that she came to the Prophet (peace and blessings be upon him) while he (peace and blessings be upon him) was in i'tikaf during the last ten days of Ramadan. He was in the mosque. Then she got up to leave, and the Messenger of Allah (peace and blessings be upon him) got up with her, until they reached near the door of the mosque which was by the door of Umm Salamah. Two men of the Ansar passed by him (peace and blessings be upon him) and greeted the Messenger of Allah (peace and blessings be upon him) with salam, then they moved on. He (peace and blessings be upon him) said: "Wait, this is Safiyyah bint Huyayy." They both said: "Subhan Allah (Glory be to Allah)! O Messenger of Allah (peace and blessings be upon him), what is this!" This weighed heavily upon them, and the Messenger of Allah (peace and blessings be upon him) said: "Indeed, Shaytan reaches into a person as far as the blood circulates, so I feared that something might enter your hearts."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8598