Saying, I will declare thy name unto my brethren, in the midst of the church will I sing praise unto thee.
Messiah declares the name of the Father, not known fully as Christ's Father, and therefore their Father, until after His crucifixion (John 20:17), among His brethren ("the church," i:e., the congregation), that they in turn may praise Him (Psalms 22:22-23). At Heb. 2:22 , the 22nd Psalm, which begins with Christ's cry, "My God, my God, why hast thou forsaken me?" passes from Christ's sufferings to His triumph, prefigured in the experience of David.
Will I sing - as leader of the choir (Psalms 8:2).