Thou shalt tread upon the lion and adder - Thou shalt be safe among dangers, as if the rage of the lion were restrained, and he became like a lamb, and as if the poisonous tooth of the serpent were extracted. Compare Mark 16:18. The word used here to denote the “lion” is a poetic term, not employed in prose. The word rendered “adder” is, in the margin, asp. The Hebrew word - פתן pethen - commonly means viper, asp, or adder. See Job 20:14, note; Job 20:16, note; compare Psalms 58:4; Isaiah 11:8. It may be applied to any venomous serpent.
The young lion - The “young” lion is mentioned as particularly fierce and violent. See Psalms 17:12.
And the dragon ... - Hebrew, תנין tannı̂yn. See Psalms 74:13, note; Job 7:12, note; Isaiah 27:1, note. In Exodus 7:9-10, Exodus 7:12, the word is rendered serpent (and serpents); in Genesis 1:21; and Job 7:12; whale (and whales); in Deuteronomy 32:33; Nehemiah 2:13; Psalms 74:13; Psalms 148:7; Isaiah 27:1; Isaiah 51:9; Jeremiah 51:34, as here, dragon (and dragons); in Lamentations 4:3, sea monsters. The word does not occur elsewhere. It would perhaps properly denote a sea monster; yet it may be applied to a serpent. Thus applied, it would denote a serpent of the largest and most dangerous kind; and the idea is, that he who trusted in God would be safe amidst the most fearful dangers, as if he should walk safely amidst venomous serpents.