**(49) And [recall] when We saved you...**
[Al] (The Family/People)
The root is ahl (family). Therefore, its diminutive is uhayyil. The ha (h) was replaced with an alif. Its usage is reserved for those of high status and importance, such as kings and their likes. Thus, one does not say "the al (family) of the cobbler" or "the cupper."
Pharaoh
A proper noun for whoever ruled the Amalekites, just as Caesar is for the King of Rome and Chosroes is for the King of Persia. Due to the tyranny of the Pharaohs, they derived the verb tafar’ana (to act like a Pharaoh) when someone becomes arrogant and tyrannical. In the poetry of some:
The wounded Moses came to him, yet he increased in the peak of his tyranny and excess of his insolence.
It is also recited as anjaynākum (We saved you) and najjaytum (you were saved).
They afflict you
From the expression sāmahu khasfan (he subjected him to humiliation/injustice). Amr ibn Kulthum said:
When the king subjects the people to humiliation, we refuse to let humiliation settle among us.
Its root is from sāma al-sil’ah (he sought the merchandise), as if it means "they seek to impose upon you."
The worst of the torment
Meaning: they desire to impose it upon you. Sū’ (worst/evil) is the verbal noun of sayyi’ (bad). One says, "I seek refuge in Allah from sū’ al-khuluq (bad character) and sū’ al-fi’l (bad action)," meaning their ugliness. The meaning of "the worst of the torment"—while all torment is bad—is the most severe and horrific of it, as if it is deemed "bad" in comparison to the rest.
They slaughter
This is an explanation of His saying: "They afflict you." Therefore, the conjunction is omitted, similar to His saying: "They imitate the saying of those who disbelieved" (Qur'an 9:30). Al-Zuhri recited it as yudhabbihūn (with light emphasis), like saying qaṭa‘tu al-thiyāb (I cut the clothes) versus qaṭṭa‘tuhā (I cut them up). Abdullah [ibn Mas'ud] recited it as yaqtulūn (they kill).
They did this to them because the soothsayers warned Pharaoh that a child would be born at whose hands his destruction would come, just as Nimrod was warned. Their efforts to protect themselves were of no avail, and what Allah willed came to pass.
The Trial
If "that" (dhālikum) refers to the actions of Pharaoh, it is a trial (affliction). If it refers to the salvation, it is a blessing.
(50) And [recall] when We parted the sea for you and saved you and drowned the family of Pharaoh while you were looking on.