John Gill Reformed Baptist @doctorgill

And from that time he sought opportunity to betray him. Luke adds, "in the absence of the multitude", Luk 22:6; in the most private manner, when he was alone, and in some solitary place, that no tumult might arise, and that there might be no danger of a rescue: for so he, and the chief priests, had consulted, and settled it, as what would be...

Albert Barnes Presbyterian @notesbybarnes

Verse 16. Sought opportunity to betray him. Luke adds, "in the absence of the multitude." This was the chief difficulty, to deliver him into the hands of the priests so as not to have it known by the people, or so as not to excite tumult. The opportunity which he sought, therefore, was one in which the multitude would not see him, or could not rescue the Saviour.