Tafsir Ibn Kathir -> Surah Al-Isra' -> The First Episode of Mischief caused by the Jews, and their Punishment for it

﴿فَإِذَا جَآءَ وَعْدُ أُولَـهُمَا﴾

(So, when the promise came for the first of the two) meaning the first of the two episodes of mischief.

﴿بَعَثْنَا عَلَيْكُمْ عِبَادًا لَّنَآ أُوْلِى بَأْسٍ شَدِيدٍ﴾

(We sent against you servants of Ours given to terrible warfare.) means, `We unleashed soldiers against you from among Our creatures who were given to terrible warfare,' i.e., they had great strength and weapons and power. They entered the very innermost parts of your homes, meaning they took possession of your land and invaded the very innermost parts of your homes, going between and through your houses, coming and going freely with no fear of anyone. This was the promise (completely) fulfilled. The earlier and later commentators differed over the identity of these invaders. Many Isra'iliyyat (reports from Jewish sources) were narrated about this, but I did not want to make this book too long by mentioning them, because some of them are fabricated, concocted by their heretics, and others may be true, but we have no need of them, praise be to Allah. What Allah has told us in His Book (the Qur'an) is sufficient and we have no need of what is in the other books that came before. Neither Allah nor His Messenger required us to refer to them. Allah told His Messenger that when (the Jews) committed transgression and aggression, Allah gave their enemies power over them to destroy their country and enter the innermost parts of their homes. Their humiliation and subjugation was a befitting punishment, and your Lord is never unfair or unjust to His servants. They had rebelled and killed many of the Prophets and scholars. Ibn Jarir recorded that Yahya bin Sa`id said: "I heard Sa`id bin Al-Musayyib saying: `Nebuchadnezzar conquered Ash-Sham (Greater Syria, including Palestine), destroying Jerusalem and killing them, then he came to Damascus and found blood boiling in a censer. He asked them: What is this blood They said: We found our forefathers doing this. Because of that blood, he killed seventy thousand of the believers and others, then the blood stopped boiling. This report is Sahih from Sa`id bin Al-Musayyib, and this event is well-known, as he (Nebuchadnezzar) killed their nobles and scholars, and did not leave alive anyone who knew the Tawrah by heart. He took many prisoners from the sons of the Prophets and others, and did many other things that would take too long to mention here. If we had found anything that was correct or close enough, we could have written it and reported it here. And Allah knows best. Then Allah says:

﴿إِنْ أَحْسَنتُمْ أَحْسَنتُمْ لاًّنفُسِكُمْ وَإِنْ أَسَأْتُمْ فَلَهَا﴾

((And We said): "If you do good, you do good for your own selves, and if you do evil (you do it) against yourselves.'') As Allah says elsewhere:

﴿مَّنْ عَمِلَ صَـلِحاً فَلِنَفْسِهِ وَمَنْ أَسَآءَ فَعَلَيْهَا﴾

(Whosoever does a righteous good deed, it is for (the benefit of) himself; and whosoever does evil, it is against himself.) ﴿45:15﴾