Malbim: He wanted to rebuke them for not giving the flock to drink [or graze], but he thought that perhaps they are from afar and are tired, or if they graze, they will not have time to return before dark.

Ha'amek Davar: Even though the well was close to Charan, it is possible that they were from elsewhere.

Ha'amek Davar: He had trained himself to speak in a loving, friendly way.