Contradiction with James 4:3
This verse indicates that prayers may not be answered when asked amiss, contradicting the notion of receiving whatever is asked for in John 16:23.
James 4:3: Ye ask, and receive not, because ye ask amiss, that ye may consume [it] upon your lusts. [lusts: or, pleasures]
Contradiction with Matthew 6:7
This verse warns against vain repetitions in prayer, suggesting there's more to receiving than simply asking as implied in John 16:23.
Matthew 6:7: But when ye pray, use not vain repetitions, as the heathen [do]: for they think that they shall be heard for their much speaking.
Contradiction with 2 Corinthians 12:8-9
Paul’s repeated unanswered request for the removal of his thorn in the flesh contradicts the immediate granting of requests suggested in John 16:23.
2 Corinthians 12:8-9: For this thing I besought the Lord thrice, that it might depart from me.
Contradiction with Matthew 26:39
Jesus Himself asked for the cup to pass from Him, yet it was not granted, seemingly contradicting John 16:23's promise.
Matthew 26:39: And he cometh unto the disciples, and findeth them asleep, and saith unto Peter, What, could ye not watch with me one hour?
Contradiction with 1 John 5:14-15
This verse conditions receiving what we ask for on it being according to God's will, in contrast to the blanket assurance given in John 16:23.
1 John 5:14-15: And this is the confidence that we have in him, that, if we ask any thing according to his will, he heareth us: [in: or, concerning]
Paradox #1
Some people might see a contradiction between John 16:23 and other parts of the Bible because it suggests asking for things directly in Jesus' name, while other passages emphasize praying directly to God or through the Holy Spirit. This could be seen as conflicting instructions on how prayer should be conducted.