Impromptu preaching

Impromptu preaching is a sermon technique where the preacher exhorts the congregation without any previous preparation. It can be aided with a reading of a Bible passage, aleatory opened or not, or even without any scriptural reference.

Impromptu preaching was practiced by the Christian apostles.

The Bible says that the Holy Spirit gives disciples the inspiration to speak:
Matthew 10:16-20
:16: Behold, I send you forth as sheep in the midst of wolves: be ye therefore wise as serpents, and harmless as doves.
:17: But beware of men: for they will deliver you up to the councils, and they will scourge you in their synagogues;
:18: And ye shall be brought before governors and kings for my sake, for a testimony against them and the Gentiles.
:19: But when they deliver you up, take no thought how or what ye shall speak: for it shall be given you in that same hour what ye shall speak.
:20: For it is not ye that speak, but the Spirit of your Father which speaketh in you.

According to some people, when Jesus says "take no thought how or what ye shall speak" he is saying that it is better not to script your speeches or sermons, but to let the Holy Spirit of your Father speak through you. Others see the expression as simply a comforting exhortation not to worry or be anxious, but to rest confident that God is in control (cf. Phil. 2:12-13). In other places the apostle Paul emphatically underscored the importance of diligent work in study and preparation (I Tim. 4:13-16; II Tim. 2:15).

Today impromptu preaching is practiced by conservative Quakers, Mennonites and some Pentecostals.