Albert Barnes Commentary John 16:12

"I have yet many things to say unto you, but ye cannot bear them now." — John 16:12 (ASV)

I have yet many things to say, and so on. There were many things pertaining to the work of the Spirit and the establishment of religion which might be said. Jesus had given them the outline; he had presented to them the great doctrines of the system, but he had not gone into details. These were things which they could not then bear. They were still full of Jewish prejudices and were not prepared for a full development of his plans.

Probably he refers here to the great changes which were to take place in the Jewish system—the abolition of sacrifices and the priesthood, the change of the Sabbath, the rejection of the Jewish nation, and so on. For these doctrines they were not prepared, but in due time they would be taught them by the Holy Spirit.