For some of them thought
 This was the thought of some of the disciples, it may be of all of them but John; 
 because Judas had the bag:
 which was for the common supply of Christ and his disciples, and for the relief of the poor; (See Gill on John 12:6). 
 That Jesus had said unto him, buy those things that we have need of
 against the feast;
 the feast of the passover, which was to be two days after; and shows, that this was not the passover which Christ now ate with his disciples: 
 or that he should give something to the poor;
 for whom Christ cared, and had a hearty concern, and for whom Judas had very little, notwithstanding his high pretensions.