Allah Cursed the Disbelievers Among the Children of Israel
Allah states that He has cursed the disbelievers among the Children of Israel long ago, and revealed this fact to His Prophets Dawud and `Isa, son of Maryam. He cursed them because they disobeyed Allah and transgressed against His creatures. Al-`Awfi reported that Ibn `Abbas said, "They were cursed in the Tawrah, the Injil, the Zabur (Psalms) and the Furqan (Qur'an)." Allah then states that during their time, their habit was that,
كَانُواْ لاَ يَتَنَـهَوْنَ عَن مُّنكَرٍ فَعَلُوهُ
(They used not to forbid one another from the evil they committed.) They did not forbid each other from committing sins and the prohibitions. Allah chastised them for this behavior, so that their behavior would not be imitated. Allah said,
Mentioned in the second verse (78) is the sad end of those from the Bani Isra'il who were involved in this error of excess and deficiency. On them fell the curse of Allah Almighty. Firstly, it came through the tongue of Sayyidna Dawud (علیہ السلام) as result of which they were transformed into swines. Then, this curse fell upon them through the tongue of Sayyidna 'Isa (علیہ السلام) the temporal effect of which was that they were transformed into monkeys. Some commentators have pointed out that the reference to the curse mentioned here as coming through only two prophets is because the context so requires. But, the fact is that the casting of curse on them began with Sayyidna Musa (علیہ السلام) and ended at the Last among Prophets ﷺ . Thus, the curse which overtook those, who were hostile to prophets or were guilty of acting excessively by making prophets sharers in Divine at-tributes, was wished verbally by four prophets one after the other.
In the last two verses (80, 81), the cultivation of deep friendship with disbelievers has been prohibited as its outcome is disastrous. It may also be indicative of the possibility that the deviation of Bani Isra'il was a result of their close friendly collaboration with disbelievers which may have affected their ways adversely and finally became the cause of their fall into the abyss.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 79–81
Frequently the reason for a people’s deviation from the right path of God is that they have been impressed by the thoughts of communities which have gone astray and seek to emulate them; while accepting the religion of God, they interpret it in such a way that it appears to be in consonance with current thinking. Thus, in the name of God’s religion, they adopt an ungodly religion. The Christians adapted their religion to the ideas of polytheistic communities and described it as God’s favoured religion. Sometimes this happens, when religion is cast in the mould of national aspirations. An example of this second type of deviation is presented by the Jews. They interpreted God’s religion in such a way that it should legitimize their worldliness. For Muslims there is no scope for inserting such interpretations in the text of God’s Book. But outside the text, they are free to follow the example of previous communities. Faith makes a man sensitive about transgression and evil. When he sees anyone committing transgression or indulging in evil, he becomes perturbed and immediately wants to prevent him from behaving in this way. He relates to evil people in terms of separation and not of friendship. But when his faith weakens, he remains sensitive only about his own self. Now, only that which adversely affects his own self-interest appears to him to be evil. He remains neutral about the evils which are directed towards others.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.