What does 1 Samuel 19:20 mean?

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. (1 Samuel 19:20 KJV)

And Saul sent messengers to take David: and when they saw the company of the prophets prophesying, and Samuel standing as head over them, the Spirit of God came upon the messengers of Saul, and they also prophesied. (1 Samuel 19:20 ASV)

Then Saul sent messengers to take David; and they saw a company of prophets prophesying, and Samuel standing as president over them; and the Spirit of God came upon the messengers of Saul, and they also prophesied. (1 Samuel 19:20 DBY)

Saul sent messengers to take David: and when they saw the company of the prophets prophesying, and Samuel standing as head over them, the Spirit of God came on the messengers of Saul, and they also prophesied. (1 Samuel 19:20 WEB)

And Saul sendeth messengers to take David, and they see the assembly of the prophets prophesying, and Samuel standing, set over them, and the Spirit of God is on Saul’s messengers, and they prophesy–they also. (1 Samuel 19:20 YLT)

Interlinear

And Saul <Sha’uwl> sent <shalach> messengers <mal’ak> to take <laqach> David: <David> and when they saw <ra’ah> the company <lahaqah> of the prophets <nabiy’> prophesying, <naba’> and Samuel <Sh@muw’el> standing <`amad> as appointed <natsab> over them, the Spirit <ruwach> of God <‘elohiym> was upon the messengers <mal’ak> of Saul, <Sha’uwl> and they also prophesied. <naba’>

Matthew Poole’s Commentary

Verse 20.  Saul sent messengers to take David: thus Saul’s wickedness and fury increased; and he that at first used only 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 Abimelech, for giving David entertainment, but that he feared the people, who had so great and unanimous a veneration for him.  

Prophesying, i.e. speaking of God, or of the things of God, by Divine inspiration; either praising God, or instructing men. Compare Nu 11:25; 1Sa 10:5.

Appointed over them, 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 beforehand, and to make good improvement of it afterwards, in both which they needed Samuel’s counsel and assistance. And whereas some might falsely 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.

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