My voice means My commands, or the words My servants speak. To hear is to obey. The Lord often likens His people to a flock, and one who is obedient and therefore willing to follow Him, a sheep of His fold. Such a one the Lord commands, "Thou shalt receive him into the church," and He gives the added words of comfort, "Him will I also receive."
A few years later than when this took place, Alma, who was the son of this Alma who then was the High Priest, said:
Yea, even wo unto all ye workers of iniquity; repent, repent, for the Lord God hath spoken it!
Behold, he sendeth an invitation unto all men, for the arms of mercy are extended towards them, and he saith: Repent, and I will receive you.
Yea, he saith: Come unto me and ye shall partake of the, fruit of the tree of life; yea, ye shall eat and drink of the bread and the waters of life freely;
Yea, come unto me and bring forth works of righteousness, and ye shall not be hewn down and cast into the fire-
For behold, the time is at hand that whosoever bringeth forth not good fruit, or whosoever doeth not the works of righteousness, the same have cause to wail and mourn.
O ye workers of iniquity; ye that are puffed up in the vain things of the world, ye that have professed to have known the ways of righteousness nevertheless have gone astray, as sheep having no shepherd, notwithstanding a shepherd hath called after you and is still calling after you, but ye will not hearken unto his voice!
Behold, I say unto you, that the good shepherd doth call you; yea, and in his own name he doth call you, which is the name of Christ; and if ye will not hearken unto the voice of the good shepherd, to the name by which ye are called, behold, ye are not the sheep of the good shepherd.
And now if ye are not the sheep of the good shepherd, of what fold are ye? Behold, I say unto you, that the devil is your shepherd, and ye are of his fold; and now, who can deny this? Behold, I say unto you, whosoever denieth this is a liar and a child of the devil.
For I say unto you that whatsoever is good cometh from God, and whatsoever is evil cometh from the devil. (Alma 5:32-40)