COMMENTARY on 12:19
A. Yusuf Ali:

Translation:
Then there came a caravan 1653 of travellers: they sent their water-carrier (for water), and he let down his bucket (into the well)...He said: "Ah there! Good news! 1654 Here is a (fine) young man!" So they concealed him 1655 as a treasure! But Allah knoweth well all that they do! 1656
Commentary:

1653  Then comes the caravan of unknown travellers-Midianite or Arab merchants travelling to Egypt with merchandise, such as the balm of Gilead in Transjordania. In accordance with custom the caravan was preceded by advance parties to search out water and pitch a camp near. They naturally went to the well and let down their bucket.

1654  The water carrier is surprised and taken aback, when he finds a youth of comely appearance, innocent like an angel, with a face as bright as the sun! What is he to make of it? Anyhow, to see him is a delight! And he shouts it out as a piece of good news. Some Commentators think that "Bushra", the Arabic word for "Good news", is a proper noun, the name of the companion to whom he shouted.

1655  It was a caravan of merchants, and they think of everything in terms of the money to be made out of it! Here was an unknown, unclaimed youth, of surpassing beauty, with apparently a mind as refined as was his external beauty. If he could be sold in the opulent slave markets of Memphis or whatever was the capital of the Hyksos Dynasty then ruling in Egypt (see Appendix IV following S. 7), What a price he would fetch! They had indeed lighted upon a treasure! And they wanted to conceal him lest he was another's slave and had run away from his master who might come and claim him! The circumstances were peculiar and the merchants were cautious. Bida'ah - stock in trade: capital; money; wealth; treasure (Cf. 12:62).

1656  To different minds the situation appeared different. Joseph must have felt keenly the edge of his brethren's treason. His father Jacob was lost in the sorrow of the loss of his best-beloved son. The brethren were exulting in their plan of getting rid of one whom they hated. The merchants were gloating over their gains. But the horizon of all was limited. Allah knew their deeds and their feelings and motives, and He was working out His own Plan. Neither the best of us nor the worst of us know whether our Destiny is leading us-how evil plots are defeated and goodness comes to its own in marvelous ways!

 

Muhammad Asad:

Translation:
AND THERE CAME a caravan; 19 and they sent forth their drawer of water, and he let down his bucket into the well - [and when he saw Joseph] he exclaimed: "Oh, what a lucky find, 20 this boy!" And they hid him with a view to selling him: but God had full knowledge of all that they were doing.
Commentary:
19  According. to the Bible (Genesis xxxvii, 25), they were "Ishmaelites" - i.e., Arabs - who "came from Gilead with their camels bearing spicery and balm and myrrh, going to carry it down to Egypt". (Gilead is the Biblical name for the region east of the Jordan.)
20  Lit., "O good news!"