The visitors played majority of the game with 10-men after goalkeepr Brad Jones was sent off in the first half.
Al Faiha took the lead in the 11th minute through Ronnie Fernandez but the champions rallied back with four goals in the second half.
Musa provided two assists for hat-trick hero Abderrazak Hamdallah, while Sultan Al Ghanam got the other goal for Al Nassr.
Also Read: Saudi League: Musa Grabs Two Assists In Al Nassr 4-1 Win At Al Faiha
“Together we will make it,”Musa tweeted after the game.
Musa, who has struggled with injuries this season has made eight league appearances for Al Nassr and is yet to open his goal account in the current the campaign.
Al Nassr occupy top spot in the league on 29 points from 13 games.