A.T. Robertson Commentary Hebrews 7:5

"And they indeed of the sons of Levi that receive the priest`s office have commandment to take tithes of the people according to the law, that is, of their brethren, though these have come out of the loins of Abraham:" — Hebrews 7:5 (ASV)

The priest's office (την ιερατειαν). LXX and Koine word from ιερευς, in N.T. only here and Lu 1:9.

To take tithes (αποδεκατοιν). Present active infinitive (in -οιν, not -ουν, as the best MSS. give it) of αποδεκατοω a LXX word (απο, δεκατοω), to take a tenth from (απο).

Brethren (αδελφους). Accusative case in apposition with λαον (people) unaffected by the explanatory phrase τουτ' εστιν (that is).

Though come out (καιπερ εξεληλυθοτας). Concessive participle (cf. 5:8) with καιπερ (perfect active of εξερχομα).