Charles H. Spurgeon on Psalms 16:4

"Drink offerings of blood." It is uncertain whether this expression is to be understood literally to be blood, which the heathen actually mixed in their libations when they bound themselves to the commission of some dreadful deed, or whether their libations are figuratively called offerings of blood to denote the horror with which the writer regarded them. —George R. Noyes, in loc. 1846.

Verse 4 (last clause). A sin rolled under the tongue becomes soft and supple, and the throat is so short and slippery a passage, that insensibly it may slide down from the mouth into the stomach; and contemplative wantonness quickly turns into practical uncleanness. —Thomas Fuller.