There was an Amir in Mecca who pronounced taslim twice. Abdullah said: Where did he get this sunnah? Al-Hakam said: There is a hadith to the effect that the Messenger of Allah ﷺ did like It.

الْحَكَمُ فِي حَدِيثِهِ إِنَّ رَسُولَ اللَّهِ ﷺ كَانَ يَفْعَلُهُ