Matthew Poole and continuators on 1 Samuel 19:20

20 And Saul sent messengers to take David : and when they saw the company of the Prophets prophesying , and Samuel standing as appointed over them , the Spirit of God was upon the messengers of Saul, and they also prophesied .

Thus Saul's wickedness and fury increased; and he that at first used onely secret practices against David, now breaks forth into open and impudent Hostilities; plainly declaring, that he neither feared God, nor reverenced Man. He would have punished Samuel, as afterwards he did Abimeleck, for giving David entertainment, but that he feared the People, who had so great and unanimous a Veneration for him.

i. e. Speaking of God, or of the things of God by Divine inspiration; either praising God, or instructing Men. Compare Numb. 11. 25. 1 Sam. 10. 5.

To instruct, moderate and direct them in those Holy exercises. For though they prophesied by Divine Inspiration, which Samuel could not govern; yet they were both to prepare and dispose themselves for it before-hand, and to make good improvement of it afterwards, in both which they needed Samuel's counsel and assistance. And whereas some might falsly pretend to those Raptures; or the Devil might transform himself into an Angel of Light, and convey some Evil or false Suggestions into some of their minds, Samuel's presence and judgment was necessary to prevent and to detect such Impostures. Besides, Samuel would by his present conjunction with them in those Holy Exercises, encourage them, and stir up others to the coveting of those Gifts, and the performance of such Religious Duties.

Being Inspired by God to do so, as wicked Balaam also was; that being wrapt up into such an extasie, their minds might be wholly taken up with those matters, and quite taken off from their design of seizing David.