Save me from the lion’s mouth - His enemies represented as fierce and ravening lions, compare Psalms 22:13,
For thou hast heard me - The word “heard” in this place is equivalent to “saved” - or saved in answer to prayer. The fact of “hearing” the prayer, and answering it, is regarded as so identical, or the one as so certainly following from the other, that they may be spoken of as the same thing.
From the horns of the unicorns - The idea here is, that he cried to God when exposed to what is here called “the horns of the unicorns.” That is, when surrounded by enemies as fierce and violent as wild beasts - as if he were among “unicorns” seeking his life - he had called upon God, and God had heard him. This would refer to some former period of his life, when surrounded by dangers, or exposed to the attacks of wicked men, and when he had called upon God, and had been heard. There were not a few occasions alike in the life of David and in the life of the Saviour, to which this would be applicable. The fact that he had thus been delivered from danger, is now urged as an argument why God was to be regarded as able to deliver him again, and why the prayer might be offered that he would do it; compare Psalms 22:9-11. To see the force of this it is not necessary to be able to determine with accuracy what is meant here by the word rendered unicorn, or whether the psalmist referred to the animal now denoted by that term. The existence of such an animal was long regarded as fabulous; but though it has been proved that there is such an animal, it is not necessary to suppose that the psalmist referred to it. Gesenius renders the word - ראם re'êm - “buffalo” (Lexicon) So also DeWette. See the notes at Job 39:9-10, where the meaning of the word is fully considered. The word occurs elsewhere only in Numbers 23:22; Numbers 24:8; Deuteronomy 33:17; Psalms 29:6; Psalms 92:10; Isaiah 34:7, in all which places it is rendered “unicorn,” or “unicorns.”