en_tn_condensed/ezk/09/06.md

mark on his head

These were the people who groaned about the abominations happening in Jerusalem. See how you translated "mark" in Ezekiel 9:4.

Begin at my sanctuary

You may need to make explicit what the people are to begin to do at the sanctuary. AT: "Begin to kill the ones who do not have the mark at my sanctuary" (See: rc://en/ta/man/translate/figs-explicit)

the elders

Possible meanings are 1) the "seventy elders of the house of Israel" (Ezekiel 8:11) or 2) any "old man" (see the beginning of the verse).