صحيح ابن خزيمه
Sahih Ibn Khuzaymah
جماع أبواب ذكر الوتر وما فيه من السننChapters on Witr and its Sunnahs
(443) بَابُ ذِكْرِ الْأَخْبَارِ الْمَنْصُوصَةِ وَالدَّالَّةِ عَلَى أَنَّ الْوِتْرَ لَيْسَ بِفَرْضٍThe chapter on explicit reports indicating that Witr is not obligatory
Hadith 1066
Imam Abu Bakr, may Allah have mercy on him, says that at the beginning of the book, I have already dictated the narration of Sayyiduna Talhah bin Ubaidullah regarding a Bedouin's question to the Noble Prophet (peace be upon him) about Islam and the Prophet's (peace be upon him) answer. The Prophet (peace be upon him) said: "Five prayers are obligatory in the day and night." He asked, "Is there any prayer obligatory upon me besides these?" The Prophet (peace be upon him) said: "No, except that you offer voluntary (nafl) prayers." Thus, the Chosen Prophet (peace be upon him) informed him that whatever is in addition to the five prayers will be considered voluntary.
