Kissing one’s thumbs when the name of the Prophet is mentioned is a bid’ah

As far as we know, there is no saheeh report from the Prophet (peace and blessings of Allaah be upon him) that when the muezzin says “Ashhadu anna Muhammadan Rasool-Allaah” we should kiss our thumbs, so doing so is a bid’ah (innovation). But it was proven that the Prophet (peace and blessings of Allaah be upon him) said, “Whoever innovates something in this matter of ours that is not part of it will have it rejected.” And Allaah is the Source of strength. May Allaah bless our Prophet Muhammad.