Did the Companions and the Successors conclude their gatherings with "the expiation of the assembly" and Surat Al-Asr, and does the absence of a hadith from the Prophet concluding with Surat Al-Asr make that an innovation?

It is recommended for a Muslim to conclude his gathering with the supplication of atonement for the assembly, as narrated from the Prophet, peace and blessings be upon him: "Glory be to You, O Allah, and with Your praise, I bear witness that there is no god but You, I seek Your forgiveness and repent to You." Also, it was the practice of the Companions, may Allah be pleased with them, that when any two of them met, they would not part until one of them recited Surat "Al-Asr" to the other. This indicates the permissibility of reciting Surat Al-Asr upon parting.