Acts 11:16 - Ellicott's Commentary On The Whole Bible

Then remembered I the word of the Lord. — The special promise referred to was that recorded in Acts 1:5. Then it had seemed to refer only to the disciples, and the Day of Pentecost had appeared to bring a complete fulfilment of it. Now Peter had learnt to see that it had a wider range, that the gift might be bestowed on those who were not of Israel, and who were not called to come outwardly within the covenant of Israel. If the baptism of the Holy Ghost had been thus given to them it implied, as the greater includes the less, that they were admissible to the baptism of water.