Yusuf is Rescued from the Well and sold as a Slave
Allah narrates what happened to Yusuf, peace be upon him, after his brothers threw him down the well and left him in it, alone, where he remained for three days, according to Abu Bakr bin 'Ayyash. Muhammad bin Ishaq said, "After Yusufs brothers threw him down the well, they remained around the well for the rest of the day to see what he might do and what would happen to him. Allah sent a caravan of travelers that camped near that well, and they sent to it the man responsible for drawing water for them. When he approached the well, he lowered his bucket down into it, Yusuf held on to it and the man rescued him and felt happy,
{"What good news! Here is a boy."}

Al-'Awfi reported that Ibn 'Abbas commented, "Allah's statement,
{So they hid him as merchandise}, is in reference to Yusufs brothers, who hid the news that he was their brother. Yusuf hid this news for fear that his brothers might kill him and preferred to be sold instead. Consequently, Yusufs brothers told the water drawer about him and that man said to his companions,
{"What good news! Here is a boy."}, a slave whom we can sell. Therefore, Yusufs own brothers sold him."
Allah's statement,
{And Allah was the All-Knower of what they did.}

states that Allah knew what Yusufs brothers, and those who bought him, did. He was able to stop them and prevent them from committing their actions, but out of His perfect wisdom He decreed otherwise. He let them do what they did, so that His decision prevails and His appointed destiny rules,
{Surely, His is the creation and commandment. Blessed is Allah, the Lord of the all that exists!}

This reminds Allah's Messenger Muhammad, that Allah has perfect knowledge in the persecution that his people committed against him and that He is able to stop them. However, He decided to give them respite, then give Muhammad the victory and make him prevail over them, just as He gave Yusuf victory and made him prevail over his brothers.
Allah said next,
{And they sold him for a Bakhs price, - for a few Dirhams}

in reference to Yusufs brothers selling him for a little price, according to Mujahid and 'Ikrimah. 'Bakhs' means decreased, just as Allah the Exalted said in another Ayah,
{shall have no fear, either of a Bakhs (a decrease in the reward of his good deeds) or a Rahaq (an increase in the punishment for his sins).}

meaning that Yusufs brothers exchanged him for a miserably low price. Yet, he was so insignificant to them that had the caravan people wanted him for free, they would have given him for free to them! Ibn 'Abbas, Mujahid and Ad-Dahhak said that,
{And they sold him}, is in reference to Yusufs brothers. They sold Yusuf for the lowest price, as indicated by Allah's statement next,
{for a few Dirhams}, twenty Dirhams, according to 'Abdullah bin Mas'ud. Similar was said by Ibn 'Abbas, Nawf Al-Bukali, As-Suddi, Qatadah and 'Atiyah Al-'Awfi, who added that they divided the Dirhams among themselves, each getting two Dirhams. Ad-Dahhak commented on Allah's statement,"