1Cor 3:10-11, 10 According to the grace of God which was given to me, as a wise master builder I have laid the foundation, and another builds on it. But let each one take heed how he builds on it. 11, For no other foundation can anyone lay than that which is laid, which is Jesus Christ.
The grace of God gave the apostle Paul the doctrine and wisdom to carefully lay “the” forever foundation. This same grace gave him temperance to rejoice when others came on to build on this foundation without strife or jealousy. This grace in addition gave him the boldness to instruct men to be careful how they build on it. This warning stemmed from the division he addressed as the Church at Corinth had divided itself into groups.
No other foundation can no man lay for there is only but one foundation of the church (Mat 16:16), laid by God (Isa 28:16). Paul’s work under God was to point to this foundation, to induce them to believe, and thus to build them upon it. His preaching laid it in their hearts. To preach Christ is to preach the fundamental or foundational truth of the church, all according to the grace given and not man’s doing to boast about.