All things. The promise is extended beyond the sphere of extraordinary miracles. In prayer; ἐν τῇ προσευχῇ: in the prayer; or, in your prayer. The use of the article may point to the prayer given by our Lord to his disciples, or to some definite form used from the earliest times in public worship (comp. Acts 1:14; Romans 12:12; 1 Corinthians 7:5; Colossians 4:2). Believing, ye shall receive. The condition for the success of prayer is stringent. A man must have no latent doubt in his heart; he must not debate whether the thing desired can be done or not; he must have absolute trust in the power and good will of God; and he must believe that "what he saith cometh to pass" (Mark 11:23). The faith required is the assurance of things hoped for, such as gives substance and being to them while yet out of sight. The words had their special application to the apostles, instructing them that they were not to expect to be able, like their Master, to work the wonders needed for the confirmation of the gospel by their own power. Such effects could be achieved only by prayer and faith. (On the general promise to faithful prayer, see Matthew 7:7-11.)
Verse 21:23-22:14
Our Lord's authority questioned: he replies by uttering three parables. (Mk 11:27-12:12; Luke 20:1-18.)