In Galatians 4:6, what does the Spirit of God's Son cry out in our hearts?

Answer: Abba, Father!

Because you are sons, God sent the Spirit of His Son into our hearts, crying out, 'Abba, Father!'

“And because you are sons, God sent the Spirit of His Son into our hearts, crying out, “Abba, Father!””— Galatians 4:6 (BSB)