Pulpit Commentary on Genesis 16:7

And the angel of the Lord. Maleach Jehovah, elsewhere styled Maleach Elohim (Genesis 21:17; Genesis 31:11); supposed but wrongly to be a creature angel (Augustine, Origen, Jerome, Hofmann, Bamngarten, Tholuck, Delitzsch, Kurtz), for the reasons chiefly

(1) that the term angel commonly designates a class of spiritual beings (Genesis 19:1; Genesis 32:1; Job 4:18; Psalm 91:11; Matthew 13:41; John 20:12, et passim);

(2) that the ἄγγελος κυρίου of the New Testament (Matthew 1:20; Luke 2:9; Acts 12:7) is always a created angel;

(3) that the meaning of the term מַלְאָך, one sent, from לָאַך, to depute (Gesenius), one through whom work is executed, from לָאַך, to work (Keil), implies a certain degree of subordination, which is afterwards more distinctly recognized (1 Chronicles 21:27; Zechariah 1:12);

(4) that the distinction between the unrevealed and the revealed God was not then developed as in later times, and particularly since the advent of Christ.