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 75:1Al-taschith--(See on Psa 57:1, title). In impending danger, the Psalmist, anticipating relief in view of God's righteous government, takes courage and renders praise. (Psa 75:1-10)
God's name or perfections are set forth by His wondrous works.
psa 75:2These verses express the purpose of God to administer a just government, and in a time of anarchy that He sustains the nation. Some apply the words to the Psalmist.
receive the congregation--literally, "take a set time" (Psa 102:13; Hos 2:3), or an assembly at a set time--that is, for judging.
psa 75:3pillars of it-- (Sa1 2:8).
psa 75:4Here the writer speaks in view of God's declaration, warning the wicked.
Lift . . . up the horn--to exalt power, here, of the wicked himself--that is, to be arrogant or self-elated.
psa 75:5speak . . . neck--insolently.
psa 75:6promotion--literally, "a lifting up." God is the only right judge of merit.
psa 75:8in the hand . . . a cup . . . red--God's wrath often thus represented (compare Isa 51:17 Jer 25:15).
but the dregs--literally, "surely the dregs, they shall drain it."
psa 75:9Contrasted is the lot of the pious who will praise God, and, acting under His direction, will destroy the power of the wicked, and exalt that of the righteous.