Changing one's intention from being a Ma'mum to being an Imam

Q 6: A Ma’mum (person being led by an Imam in Prayer) joined ‘Asr (Afternoon) Prayer during the fourth Rak‘ah (unit of Prayer) then another man came and started praying behind him. Is it permissible for the first praying person to change his intention from being a Ma’mum to being an Imam (the one who leads congregational Prayer)?

A: It is permissible for whoever misses congregational Salah (Prayer) and cannot find anybody else to start a new congregation with, to pray (as a Ma’mum) behind a person who is making up for the Rak‘ahs that they have missed, after the Taslim (salutation of peace ending the Prayer) of the Imam. Proof for the foregoing is that the Prophet (peace be upon him) was offering Salah during the night and Ibn ‘Abbas came and prayed behind him. It is noteworthy that offering Salah in congregation is more rewarded.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.