It is narrated from Abd al-Rahman bin Abi Amrah al-Najjari that he asked Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) about witr, and he said: It is a most excellent and beautiful practice, which the Prophet (peace and blessings be upon him) and the Muslims after him acted upon, but it is not obligatory. This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it, and it also has supporting narrations (shawahid).