Sheikh bin Baaz was asked;
If an individual finished from his prayer, and wanted to make the tasleem, what does he do? Does he say, “As salaamu alaikum wa rahmatullahi wa barakaatuh” on his right and his left? Or does he only say, “As salaamu alaikum wa rahmatullahi ” What is the ruling of the prayer of one who adds on this statement – wa barakaatuh?
His response was;
That which is known from the Sunnah is only the statement “as salaamu alaikum wa rahmatullahi both to the left and the right. As far as adding on the statement – wa barakaatuh – there is a difference of opinion among the Scholars. Alqama bin Waail narrated on the authority of his father that the Prophet (صلى الله عليه و سلم) said the entirety of the statement “As salaamu alaikum wa rahmatullahi wa barakaatuh.” The problem is that about this particular narration, the scholars disagree as to whether he actually heard it from his father or not. Some of the Scholars say that the chain of narration has been broken therefore it is not said to be acceptable. So that which should be done by the believer is not to add on the statement “wa barakaatuh”, but rather to stop at “wa rahmatullahi.” As far as the one that adds onto it thinking that it is correct or ignorant of the ruling, there is no harm in this, and his prayer is correct. Though, that which is more befitting and the safest opinion is not to add onto the original statement, so that you do not fall into something that the scholars differ in to begin with.
[Taken from Majmou al Fatawah by Sheikh bin Baaz]
[Translated by Abu Abdillah Abdul Lateef]