John Mark
Mark 3:2ESV·traditional attribution

And they watched Jesus, to see whether he would heal him on the Sabbath, so that they might accuse him.

Matthew Henry Presbyterian @wholebiblehenry

Here, as before, we have our Lord Jesus busy at work in the synagogue first, and then by the sea side; to teach us that his presence should not be confined either to the one or to the other, but, wherever any are gathered together in his name, whether in the synagogue or any where else, there is he in the midst of them.

Commenting on Mark 3:1-12

John Gill Reformed Baptist @doctorgill

And they watched him,.... The ruler of the synagogue, and the principal men in it; particularly the Scribes and Pharisees, who followed him wherever he went; they observed him diligently, and kept their eyes upon him; this lame man being in the synagogue, to see whether he would heal him on the sabbath day; which, knowing his readiness to do good, they might expect he...

Adam Clarke Methodist @methodicalclarke

They watched him - Παρετηρουν αυτον, they maliciously watched him. See on Luk 14:1 (note).