Hebrews 13:15-16 → Leviticus 7:12

The lexical contact is a verbatim two-word Septuagint phrase. Hebrews 13:15 asks for a θυσία αἰνέσεως, "sacrifice of praise" (G2378 + G133) — and verified at the vault's LXX shelf, θυσία αἰνέσεως is precisely how the Greek Leviticus renders zeḇaḥ ha-tôdâ, the thanksgiving offering of Leviticus 7:12 (H2077 + H8426). The phrase recurs in the Psalms and Chronicles, so Leviticus 7:12 is its legislative origin rather than its only occurrence; but Leviticus is where the offering is defined, which is why the pair files here. Hebrews then does something more interesting than substitution. Verse 15 gives the tôdâ a new material — no animal, but "the fruit of lips that confess His name" (καρπὸς χειλέων, itself lifted from Hosea 14:2 LXX) — and then verse 16 adds a second clause most readers hear as an unrelated afterthought: "And do not neglect to do good and to share with others, for with such sacrifices God is pleased." It is not an afterthought. It is the rest of Leviticus 7. The distinctive rule of the thanksgiving offering is that its meat "must be eaten on the day he offers it; none of it may be left until morning" (7:15) — a whole animal, one day, no way to eat it alone. Israelite thanksgiving was constructed so that it had to be shared before sundown. So Hebrews 13:15-16 is not praise plus charity; it is the tôdâ intact, with both of its halves — words upward, food outward — carried into the new covenant. The Contrast is the ground on which it stands: three verses earlier the author says "We have an altar from which those who serve at the tabernacle have no right to eat" (13:10), and Jesus suffered "outside the city gate" (13:12). The offerings of verses 15-16 are possible only because the sacrifice they would once have accompanied has been made and cannot be repeated. This is why the exhortation is not a burden. A thank offering is the one sacrifice you bring when something has already happened to you; nobody offers a tôdâ to obtain a rescue. God asks for praise and open-handedness from His people for the same reason He built gratitude to be un-hoardable — because delight that has to be spent is the shape joy takes when the rescue is already done.