In a sweet Instagram video shared on Friday, Mooney is seen singing his and Dan Smyers' song "When I Pray for You" to his newborn son Abram Shay Mooney, as Abram sleeps on his chest.
"Grateful doesn't begin to cover it," Mooney wrote in the caption.
Billingsley also shared the video on her instagram and wrote in the caption, "First song sang to the newest family member… Abram Shay, you're so loved and so prayed over, baby boy. Thankful for all that God has done for us this week."
The couple, who tied the knot in 2017, announced they were expecting their third child last August.
They are already parents to two boys, Asher, 5, and Ames, 2.