Albert Barnes on John 16:23

In that day. After my resurrection and ascension.

Ye shall ask me nothing. The word rendered ask here may have two significations, one to ask by way of inquiry, the other to ask for assistance. Perhaps there is reference here to both these senses. While he was with them they had been accustomed to depend on him for the supply of their wants, and in a great degree to propose their trials to him, expecting his aid. See Mt 8:25, Jn 11:3. They were also dependent on his personal instructions to explain to them the mysteries of his religion, and to remove their perplexities on the subject of his doctrines. They had not sought to God through him as the Mediator, but they had directly applied to the Saviour himself. He now tells them that henceforward their requests were to be made to God in his name, and that he, by the influences of his Spirit, would make known to them what Jesus would himself do if bodily present. The emphasis in this verse is to be placed on the word "me." Their requests were not to be made to him, but to the Father.

Whatsoever ye shall ask, &c. See Jn 14:13.