Richardson, Richardson and Bentley note that in the Book of Mormon the use of the expression "lay hold" is authentic (see also Helaman 3:29 and Mormon 7:8). Had Joseph Smith or any of his contemporaries written the Book of Mormon rather than ancient prophets, he might have written that people were exhorted to "accept" the word of God or to "receive" it. Yet "lay hold" upon the "word of God" or "upon every good thing" was a common expression among ancient peoples of the Middle East. For example, a Jewish document urges the people to "take hold of the way of God." (See Nibley, Since Cumorah, pp. 166-167). [Allen H. Richardson, David E. Richardson and Anthony E. Bentley, 1000 Evidences for the Church of Jesus Christ of Latter-day Saints: Part Two-A Voice from the Dust: 500 Evidences in Support of the Book of Mormon, p. 264]
Note* In Moroni 7, Mormon speaks of how if "ye will lay hold upon every good thing, and condemn it not, ye certainly will be a child of Christ" (Moroni 7:19). In just 7 verses he uses this phrase 4 times. It is interesting that in the entire Book of Mormon, the phrase "lay hold [up]on every good [thing]" is used only 5 times: 4 by Moroni writing a few words of his father Mormon (Moroni 7:19, 20, 21, 25), and by Moroni in his last exhortation to his brethren the Lamanites:
And again I would exhort you that ye would come unto Christ, and lay hold upon every good gift, and touch not the evil gift, nor the unclean thing.
And awake, and arise from the dust, O Jerusalem; yea, and put on thy beautiful garments, O daughter of Zion; and strengthen thy stakes and enlarge thy borders forever, that thou mayest no more be confounded, that the covenants of the Eternal Father which he hath made unto thee, O house of Israel, may be fulfilled.
Yea, come unto Christ, and be perfected in him, and deny yourselves all ungodliness; and if ye shall deny yourselves of all ungodliness and love God with all your might, mind and strength, then is his grace sufficient for you, that by his grace ye may be perfect in Christ; and if by the grace of God ye are perfect in Christ, ye can in nowise deny the power of God.
And again, if ye by the grace of God are perfect in Christ, and deny not his power, then are ye sanctified in Christ by the grace of God, through the shedding of the blood of Christ, which is in the covenant of the Father unto the remission of your sins, that ye become holy without spot. (Moroni 10:30-33)
The phrase "lay hold upon every good thing," or something similar, is not found in the Bible, although their are two instances worth citing. In Proverbs 3:18 we find, "[Wisdom] is a tree of life to them that lay hold upon her; and happy is every one that retaineth her." In Hebrews 6:10-20 we find,
For God is not unrighteous to forget your work and labour of love, which ye have shewed toward his name, in that ye have ministered to the saints, and do minister.
And we desire that every one of you do shew the same diligence to the full assurance of hope unto the end;
That ye be not slothful, but followers of them who through faith and patience inherit the promises.
For when God made promise to Abraham, because he could swear by no greater, he sware by himself, Saying, Surely blessing I will bless thee, and multiplying I will multiply thee.
And so, after he had patiently endured, he obtained the promise.
For men verily swear by the greater: and an oath for confirmation is to them an end of all strife.
Wherein God, willing more abundantly to shew unto the heirs of promise the immutability of his counsel, confirmed it by an oath:
That by two immutable things, in which it was impossible for God to lie, we might have a strong consolation, who have fled for refuge to lay hold upon the hope set before us.
Which hope we have as an anchor of the soul, both sure and stedfast, and which entereth into that within the veil;
Whither the forerunner is for us entered, even Jesus, made an high priest for ever after the order of Melchisedec.
It is significant that all of the instances in the Bible and the Book of Mormon where "lay hold upon" is used speak of obtaining or "laying hold upon" the knowledge of Christ, with both Paul and Moroni implying that it involves a covenant process. [Alan C. Miner, Personal Notes]