The Apostle Paul
1 Corinthians 15:3BSB·traditional attribution

For what I received I passed on to you as of first importance: that Christ died for our sins according to the Scriptures,

John Gill Reformed Baptist

For I delivered unto you first of all,.... Not only in the first place as to order; but among the chief and principal things, as the words will bear to be rendered, this was insisted on in his ministry; this was one he after relates, even a crucified Christ, or the doctrine of his dying for the sins of his people; and which he mentions...

Jamieson-Fausset-Brown Reformed

I delivered unto you--A short creed, or summary of articles of faith, was probably even then existing; and a profession in accordance with it was required of candidates for baptism (Act 8:37). first of all--literally, "among the foremost points" (Heb 6:2). The atonement is, in Paul's view, of primary importance. which I . . . received--from Christ Himself by special revelation (compare Co1 11:23).

Albert Barnes Presbyterian

Verse 3. For I delivered unto you. . First of all. Among the first doctrines which I preached. As the leading and primary doctrines of Christianity. That which I also received. Which had been communicated to me. Not doctrines of which I was the author, or which were to be regarded as my own.