John Calvin Commentary John 4:41

"And many more believed because of his word;" — John 4:41 (ASV)

And many more believed. From what followed, it is evident that Christ’s compliance with their wish was very fitting; for we see how much fruit was reaped from the two days he granted to their request. By this example, we are taught that we should never refrain from working when we have the power to advance the kingdom of God; and if we are afraid that our readiness to comply may be liable to unfavorable reports, or may often prove useless, let us ask Christ for the Spirit of counsel to direct us.

The word believe is here used in a different sense; for it means not only that they were prepared for faith, but that they actually had genuine faith.