1 Samuel 19:1

Now Saul spoke to Jonathan his son and to all his servants about killing David, but Saul's son Jonathan {liked David very much}.

1 Samuel 18:1

{When} he finished speaking to Saul, the soul of Jonathan became attached to the soul of David, and Jonathan loved him as his [own] soul.

1 Samuel 18:9

So Saul was watching David [with suspicion] from that day onward.

Treasury of Scripture Knowledge

Summary

And Saul spake to Jonathan his son, and to all his servants, that they should kill David.

Bible References

And saul

Ecclesiastes 9:3
This [is] the {injustice} that is done under the sun: the same fate [comes] to everyone. Also the hearts of {humans} are full [of] evil; delusion [is] in their hearts during their lives, and then they die.
Jeremiah 9:3
And they bend their tongue [like] their bow, [for] falsehood and not truth is superior in the land, for they go forth from evil to evil, and they do not know me," {declares} Yahweh.
2 Timothy 3:13
But evil people and imposters will progress to the worse, deceiving and being deceived.