Seeking forgiveness when getting up from a gathering

It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever sits in a gathering in which there is much idle talk, and then, before getting up from it, one of them says these words: 'Subhanaka Rabbana wa bi hamdik, la ilaha illa ant, astaghfiruka thumma atubu ilayk' (Glory be to You, our Lord, and praise; there is no god but You; I seek Your forgiveness and then I repent to You), the sins committed in that gathering are forgiven for him."
This chain is sahih (authentic) on the condition of Imam Muslim; however, Imam Bukhari declared it defective because of the narration of Wuhayb, which makes it a saying of Ka'b al-Ahbar.

It is narrated from Sayyiduna Jubayr bin Mut'im (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever says these words: 'Subhanallahi wa bi hamdih, subhanaka Allahumma wa bi hamdik, ashhadu an la ilaha illa ant, astaghfiruka wa atubu ilayk' (Glory be to Allah and praise be to Him; glory be to You, O Allah, and praise; I bear witness that there is no god but You; I seek Your forgiveness and I repent to You); if he says them in a gathering of remembrance, they will be like a seal (a safeguard) upon the good of that gathering, and if he says them in a gathering of idle and useless talk, they will be an expiation for his sins."
This hadith is sahih (authentic) on the condition of Imam Muslim, but the two Shaykhs did not record it.