Did Asma bint Abi Bakr practice temporary marriage (mut'ah)? And did the Companions do so during the time of the Messenger of Allah, peace and blessings be upon him? And was mut'ah lawful then prohibited? And were there proofs of its prohibition mentioned in the Sahihayn (Bukhari and Muslim)?

This narration from Asma -may Allah be pleased with her- was reported by An-Nasa'i, and her words do not imply her practice of Mut'ah (temporary marriage). Rather, it might mean her declaration of its permissibility in the Prophetic era before its abrogation. Indeed, some of the Salaf (early Muslims) used to issue fatwas (religious edicts) permitting it, but then consensus was established on its prohibition and invalidity.