D&C 88

In preparation for the School of the Prophets, or what I consider to be a priesthood leadership meeting, the Lord said -

"...I give unto you, who are the first laborers in this last kingdom, a commandment that you assemble yourselves together, and organize yourselves, and prepare yourselves, and sanctify yourselves; yea, purify your hearts, and cleanse your hands and your feet before me, that I may make you clean..."  (Doctrine and Covenants | Section 88:74)

Adding -

"Also, I give unto you a commandment that ye shall continue in prayer and fasting from this time forth."  (Doctrine and Covenants | Section 88:76)

So that -

"...you shall teach one another the doctrine of the kingdom.
78 Teach ye diligently and my grace shall attend you, that you may be instructed more perfectly in theory, in principle, in doctrine, in the law of the gospel, in all things that pertain unto the kingdom of God, that are expedient for you to understand..."  (Doctrine and Covenants | Section 88:77 - 78)