This revelation was not included in the Book of Commandments. It was published in the 1835 Doctrine and Covenants with revised wording. Footnotes and commentary can be found in Joseph Smith's 1828-1843 Revelations
From BCR, 93-94 (cf. LDS and RLDS D&C 57)
Revelation received at Independence, Jackson County, Missouri,
on 20 July 1831 indicating the place of the City of Zion
and the gathering
Commandment Given Missorie [Missouri] Independence Jackson Co[unty] July 20th 1831 giving directions to the Bishop & Agent how to preceed [proceed] concerning purchuseing [purchasing] Lands &c. &c.
 Hearken Oh ye Elders of my Church, saith the lord your God, Who have assembelled assembled yourselves together, according to my commandments in this land which is the land of Missorie [Missouri] which is the Land which I, have appointed & consecrated for the gathering of the Saints
 Wherefore, this is the land of promise & the place for the City of Zion.  & thus saith the Lord your God. If ye will receive wisdom here is wisdom. Behold the place which is now called Independence is the centre [center] place, & the spot for the Temple is lying westward upon a lot which is not far from the court-house.
 Wherefore it is wisdom that the land should be purchased by the saints & also every tract lying westward even unto the line run[n]ing directly betwe[e]n Jew & gentile  and also every tract bordering by the Prairies in as much as my Deciples [Disciples] are enabled to buy lands. Behold this is wisdom that they may obtain it for an everlasting inheritance
 & let my Servent Sidney Gilbert stand in the office which I have appointed him to receive moneys to be an agent unto the church to buy lands in all the regions round about in as much as can be in righteousness, & as wisdom shall direct.
 And let my Servent Edward [Partridge] stand in the office which I have appointed him to divide unto the saints their inheritance even as I have commanded & also them whom he has appointed to assist him
 And again verily I say unto you let my servent Sidney Gilbert plant himself in this place, & establish a store that he may sell goods without fraud that he may obtain money to buy lands for the good of the Saints & that he may Obtain provisions & whatsoever things the Deciples ] Disciples may need to plant them in their inheritance
 & also let my servent Sidney [Gilbert] obtain a license (behold here is wisdom & whoso readeth let him understand) that he may send goods also unto the lamanites even by whom he will as clerks employed in his service  & thus the gospel may be preached unto them.
 And again verily I say unto you let my servent William [W. Phelps] also be planted in this place & be established as a Printer unto the Church  & lo if the world receiveth his writings (behold this is wisdom) let him obtain whatsoever he can obtain in righteousness for the good of the saints.  and let my servent Oliver [Cowdery] assist him even as I have commanded in Whatsoever place I shall appoint unto him to copy & to correct & select &c that all things may be right before me as it shall be proved by the Spirit through him  & thus let those of whom I have spoken be planted in the Land of Zion as speedily as can be with their families to do these things even as I have spoken
 And now concerning the gethering [gathering] let the bishop & the agent make preperations [preparations] for those families which have been commanded to come to this land as soon as pos[s]ible & plant them in their inheritance  & unto the residue of both Elders & members further directions shall be given hereafter even So Amen