Paul said, John indeed baptized [administered] the baptism of a change of mind, telling the people to believe on him that was to come after him, that is, on Jesus.

Whose

I indeed baptize you with water to a change of mind; but he that comes after me is mightier than I, whose shoes I am not fit to bear; he shall baptize you with the Holy Spirit, and fire;

and preached, saying, After me comes one mightier than I, the strings of whose shoes I am not fit to stoop down and untie;

John answered all, saying, I indeed baptize you with water, but a mightier than I is coming, the strings of whose shoes I am not fit to untie; he shall baptize you with the Holy Spirit and fire.

General references

and preached, saying, After me comes one mightier than I, the strings of whose shoes I am not fit to stoop down and untie;

This is he of whom I said, After me comes a man who was before me, for he was before me.