Is adding "wa barakatuh" after "Al-salamu alaykum wa rahmatullah" when concluding the prayer an innovation (bid‘ah)? And what is the Sunnah of the Prophet regarding this?

The form of Taslim (salutation) that was narrated from the Prophet, peace and blessings be upon him, is "As-salamu alaykum wa rahmatullahi wa barakatuh" to the right, and "As-salamu alaykum wa rahmatullah" to the left, as stated in Sunan Abi Dawud from Wa'il ibn Hujr, and authenticated by Al-Albani. This is a sound addition from a just narrator, and a group of scholars have affirmed it.