New Defender's Study Bible Notes
15:10 again he saith. This quote is from the song of Moses, as he prepared to die (Deuteronomy 32:43). He had led Israel to its promised land, and now, in the final verse of his great song, he exhorted all the nations to rejoice with God’s chosen nation, for in Abraham’s seed would all nations be blessed. Note also that Paul quotes this exhortation as coming directly from God, even though it was Moses’ song, thus confirming the divine inspiration of Moses’ writings near the very end of the Pentateuch.