'First' in the Bible

I went up [to Jerusalem] because of a [divine] revelation, and I put before them the gospel which I preach among the Gentiles. But I did so in private before those of reputation, for fear that I might be running or had run [the course of my ministry] in vain.

So we, when we were young, were kept under the first rules of the world;

But now that you have come to have knowledge of God, or more truly, God has knowledge of you, how is it that you go back again to the poor and feeble first things, desiring to be servants to them again?

Believers, I beg of you, become as I am [free from the bondage of Jewish ritualism and ordinances], for I have become as you are [a Gentile]. You did me no wrong [when I first came to you; do not do it now].

Ye know how through infirmity of the flesh I preached the gospel unto you at the first.