John Gill Commentary Genesis 26:21

"And they digged another well, and they strove for that also. And he called the name of it Sitnah." — Genesis 26:21 (ASV)

And they dug another well That is, Isaac's servants: and strove for that also ; the herdsmen of Gerar disputed their right to that also, and strove to get it from them: and he called the name of it Sitnah ; which signifies "hatred", it being out of hatred and malice to him that they gave him so much trouble; from this word Satan has his name, and these men were of a diabolical spirit, envious, spiteful, and malicious.