What Book of Mormon verse says by their works ye shall know them?

Answer 1

This exact phrasing is not in The Bible, the closest being "by their fruits..." :-

Mat 7:15 Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.

Mat 7:16 Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles?

Mat 7:17 Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.

Mat 7:18 A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit.

Mat 7:19 Every tree that bringeth not forth good fruit is hewn down, and cast into the fire.

Mat 7:20 Wherefore by their fruits ye shall know them.

Mat 7:21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.

Mat 7:22 Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?

Mat 7:23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.

Answer 2

Yes it is, by observing how a man acts,speaks, dresses, is obeydient to God's commandments one may know the character of that man. You may not know him personaly, but by observation and listening one may come to know that man. Your question is referring to whether they are of God or of Satan. Matthew 7:15-23

Answer 3

Matthew 7:16-20 - "You will know them by their fruits. Do men gather grapes from thornbushes or figs from thistles? Even so, every good tree bears good fruit, but a bad tree bears bad fruit. A good tree cannot bear bad fruit, nor can a bad tree bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. Therefore by their fruits you will know them." [NKJV]

Answer 4

That phrase is said a few times in the scriptures.

Moroni 7:5 says "For I remember the word of God which saith by their works ye shall know them; for if their works be good, then they are good also."

Doctrine and Covenants 18:38 says "And by their desires and their works you shall know them."

There are many scriptures which essentially mean the same thing, such as:

Matthew 12:33 "Either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt: for the tree is known by his fruit."

Matthew 7:16 & 7:20 and 3 Nephi 14:16 & 14:20 say "by their fruits ye shall know them"