Numbers 29:13 Second Temple Literature: On Flight and Finding & On the Migration

[186] He also proclaims the ten-fold seven, telling in this passage of seventy palm-trees by the springs, and in another of the Divine Spirit of prophecy bestowed on only seventy elders (Num. 11:16), and again of seventy calves offered as victims at the Feast of Tabernacles arranged in divisions following a regular series: for they are not all sacrificed at once, but on different days, beginning with thirteen bull-calves (Num. 29:13 ff.); for in this way, the number being diminished by one every day up to the seventh, the aggregate of seventy would be made up.

[202] Sacrifices and dues paid to God are determined by this number, whenever the ripe fruits of the soul are gathered in and collected; for it is prescribed at the Feast of Tabernacles, over and above the other sacrifices, to offer seventy young bullocks as a burnt offering (Num. 29:13–36). The bowls of the princes are fashioned in keeping with the principle of seventy—for each of them is of the weight of seventy shekels (Num. 7:13 ff.)—since everything in the soul that tends to peace and friendship and agreement has a truly weighty power of attraction, that sacred principle set forth by seventy, which Egypt, the virtue-hating and passion-loving nature, is represented as mourning over; for among them mourning is reckoned as lasting seventy days (Gen. 50:3).