Answer:
"The Selling of Joseph" is a text written by Samuel Sewall, around the 1700´s as an appeal against the slave trade, and slavery in general. This document, published in New England, came as a protest against the use of slavery, and also in outcry against the case of a specific slave, Adam and his wife, who had been placed into bondage unjustly and been promised, after seven years, to be set free by his master, if he behaved. The promise was not kept and a legal battle ensued between John Saffin, the owne of Adam, and Sewall, who opposed what had happened to this couple.
In order to enforce his views on slavery, and particularly on this case, Seawall used the Bible, particularly the Old Testament, at Exodus, to prove to the society of his time that slavery, "Man Stealing", was a crime, and it was against God´s law, and therefore could not be justified at all. So the meaning if this particular excerpt is to use the response from God towards the case of Joseph´s selling to the merchants as a slave, His condemnation of such an atrocity, to showcase that likewise, God, opposed slavery, and therefore, this institution should be abolished.