Thy first father; either,
1. Adam, from whom the guilt and filth of sin is propagated to thee; or rather,
2. Abraham, who might well be called the first father of the Israelites, because they all descended from him, had all their right and title to God's ordinances and promises, and other special privileges, from God's covenant made with Abraham and with his seed, and who is oft emphatically called their father, as Joshua 24:2 Isaiah 51:2, &c; and the Jews gloried in and trusted to that relation which they had to Abraham, as we read, Matthew 3:9 1 Thessalonians 8:33, and elsewhere. And this agrees well with the foregoing context. For having sufficiently intimated that they had no merits of their own, he now addeth, that even their father Abraham, to whose merits they trusted, had no merits of his own, nor any occasion of boasting; for he also was a sinful man, and hath left some instances of his failings. Or the first father may be put collectively for their forefathers; and so he tells them, that as they were sinners, so also were all their progenitors, yea, even the best of them, Abraham, and David, and others, for whose sakes they expected to be pardoned and rewarded. And this indeed is usual with God, to upbraid the Israelites with the sins of their fathers. Thy teachers; thy priests and prophets; who were their intercessors with God, and who were generally presumed to be the holiest part of that people; and therefore if these were transgressors, the people had no reason to fancy themselves to be innocent.