Radak

I will declare Thy name to my brethren: In the midst of the congregation will I praise Thee. – When Thou shalt deliver me from the lion's mouth and from the horns of the wild oxen, when Thou dost bring me out of exile, then I will declare Thy name to my brethren, I will praise Thee in the midst of the congregation. My brethren are the children of Edom, amongst whom we are in exile. So also the children of Ishmael and the children of Keturah, for all are the children of our father Abraham. Or its interpretation may be: We who are in exile will declare the miracles and wonders God has wrought for us in our exile to the Ten Tribes who are in exile, in refreshment and union, and upon whom the hand of the nations has not pressed heavily as upon us.