A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
psa 57:1Altaschith--or, "Destroy not." This is perhaps an enigmatical allusion to the critical circumstances connected with the history, for which compare Sa1 22:1; Sa1 26:1-3. In Moses' prayer (Deu 9:26) it is a prominent petition deprecating God's anger against the people. This explanation suits the fifty-eighth and fifty-ninth also. Asaph uses it for the seventy-fifth, in the scope of which there is allusion to some emergency. Michtam--(See on Psa 16:1, title). To an earnest cry for divine aid, the Psalmist adds, as often, the language of praise, in the assured hope of a favorable hearing. (Psa 57:1-11)
my soul--or self, or life, which is threatened.
shadow of thy wings-- (Psa 17:8; Psa 36:7).
calamities--literally, "mischiefs" (Psa 52:2; Psa 55:10).
psa 57:2performeth--or, completes what He has begun.
psa 57:3from . . . swallow me up--that pants in rage after me (Psa 56:2).
mercy and . . . truth-- (Psa 25:10; Psa 36:5), as messengers (Psa 43:3) sent to deliver him.
psa 57:4The mingled figures of wild beasts (Psa 10:9; Psa 17:12) and weapons of war (Psa 11:2) heighten the picture of danger.
whose . . . tongue--or slanders.
psa 57:5This doxology illustrates his view of the connection of his deliverance with God's glory.
psa 57:6(Compare Psa 7:15; Psa 9:15-16).
psa 57:7I will . . . praise--both with voice and instrument.
psa 57:8Hence--he addresses his glory, or tongue (Psa 16:9; Psa 30:12), and his psaltery, or lute, and harp.
I myself . . . early--literally, "I will awaken dawn," poetically expressing his zeal and diligence.
psa 57:9As His mercy and truth, so shall His praise, fill the universe.