The Quran

۞ أَلَم تَرَ إِلَى الَّذينَ نافَقوا يَقولونَ لِإِخوانِهِمُ الَّذينَ كَفَروا مِن أَهلِ الكِتابِ لَئِن أُخرِجتُم لَنَخرُجَنَّ مَعَكُم وَلا نُطيعُ فيكُم أَحَدًا أَبَدًا وَإِن قوتِلتُم لَنَنصُرَنَّكُم وَاللَّهُ يَشهَدُ إِنَّهُم لَكاذِبونَ

Muhammad Asad

ART THOU NOT aware of how those who would always dissemble [their real feelings]¹ speak to their truth-denying brethren from among the followers of earlier revelation:² "If you are driven away, we shall most certainly go forth with you, and shall never pay heed to anyone against you; and if war is waged against you, we shall most certainly come to your succour." But God bears witness that they are most flagrantly lying:

I.e., the hypocrites of Medina (see introductory note as well as next note).
The Banu 'n-Nadir. From the construction of the next verse it appears that the whole of this passage (verses 11-14) was revealed before the actual advance of the Muslims against the Nadir strongholds: verses 12-14 might be of a prophetic nature, predicting what was yet to happen (Zamakhshari). Alternatively, the passage may be understood in a wider, timeless sense, applying to the falsity and futility inherent in all "alliances" between, on the one hand, people who openly deny the truth and, on the other, half-hearted waverers who have neither the will to commit themselves to a spiritual proposition nor the moral courage to declare openly their lack of belief.