Patristic
“If he "therefore emptied himself, assuming the form of a slave," he was not coerced but was of his own accord made the Son of Man, existing as God's equal in the form of God. Therefore you have the Son expressing in himself the faith proper to humans.”
Historical Christian Faith commentaries database, on Phil 2:7 (ON THE TRINITY 17)
PD · Historical Christian Faith commentaries database ↗