To save space in my books, I sometimes refer to online resources. These are the resources regarding the trip from Harmony to Fayette during which David Whitmer, Joseph Smith, and Oliver Cowdery met the divine messenger who was taking the abridged plates to Cumorah.
Here's an overview.
In May 1829, Joseph Smith, Jr., and Oliver Cowdery were translating the plates at Joseph's home in Harmony, PA.
showed it to his sisters and brothers and asked their advice as to what it would be best for him to do his said why know you have sowed as much wheat as you can harrow in tomorrow and next day and then you have a quantity of plaster to spread that is much needed on your land and you cannot go unless you get an evidence from God that it is very necessary.
In the morning he went to the field and found that he had 2 heavy days work before him He then asked the lord to enable him to do this work sooner than the same work had ever been done on the farm before and he would receive it as an evidence that it was the will of God for him to engage in forwarding the work which was begun by Joseph Smith. he then fastened his horses to the harrow and drove round the whole field he continued on till noon driving all the way round at every circuit but when it came to be time to eat dinner he discovered to his surprize that he had harrowed in full half the wheat. after dinner he again went on as before and by evening he finnished the whole 2 days work
of the fact> could not believe it till he examined for himself and ascertained that it was actually the fact Well said his there must be some overruling power in this thing and I think you had better go as soon as you get your plaster paris sown and bring up the man <with his scribe> To this also agreed The next morning as soon as breakfast was over he took the half bushel measure under his arm and went out to the place where he supposed the plaster to be as he knew exactly where he had left it 24 hours previous but when he came to look for it behold it had entirely disappeared every vestige of it was gone from the spot where he left it he ran to his sisters house a few yards distant and enquired if she knew anything of what had become of the plaster paris which had deposited near there Why said she in surprise you sowed it all yesterday at it was all sown by some one for the the children came and begged me to go out and look at some men that were sowing plaster in the field for said they Mother you never saw anybody sow plaster as fast as they do in your life I went and I I did see three men to work in the field as the children said but suposing that you had employed some assistance because of your hurry to get your work done I passed into the house without giving any further attention to the subject. made considerable enquiry but not being able to ascertain who had done it he related the circumstance to his who was quite as much at a loss to determine how the thing was brought about as he was but there was not a doubt upon the mind one of the family of there being an exertion of supernatural power connected with the operation and all hands went about preparing for his Journey he was soon on his way and in 2 days he arrived there without injuring his horses in the least although the distance was 135 miles
Lucy Mack Smith (1845) explains that Joseph was told through the Urim and Thummim to contact David Whitmer. Joseph gave the abridged plates to a divine messenger before leaving Harmony.
*You can find this account in these references, although apparently not transcribed exactly: "Edward Stevenson Interview (1) 22-23 December 1877, Richmond, Missouri Diary of Edward Stevenson," LDS Church Archives, Lyndon W. Cook, ed., David Whitmer Interviews, 1993, p. 13; also Dan Vogel, ed., Early Mormon Documents, 2003, vol. v, p. 30.