Albert Barnes Commentary Psalms 105:15

"[Saying], Touch not mine anointed ones, And do my prophets no harm." — Psalms 105:15 (ASV)

Saying, Touch not mine anointed - That is, this was the language of his “providence.” It was as though God had said this. It is not meant that this was said in so many words, but this is the “poetic” form of representing the dealings of Providence. Compare Genesis 26:11.

The word “anointed” here means that God had, as it were, set them apart to his service, or that they were to him as kings, priests, and prophets—sacred people, belonging to God. The “language” is not found in the Old Testament as applied to the patriarchs, but the “idea” is fairly implied there: that they belonged to God as sacred and holy men.

And do my prophets no harm - As if God had thus spoken to them, and called them prophets. That is, they belonged to God as a sacred order: they were separate from other men, and God regarded them as his own.