The False Promise of Support the Hypocrites gave to the Jews
Allah states that the hypocrites, Abdullah bin Ubayy and his like, sent a messenger to Bani An-Nadir promising them help.
Allah the Exalted said,
ألم تر إلى الذين نافقوا يقولون ﻻخوانهم الذين كفروا من أهل الكتاب
لين أخرجتم لنخرجن معكم وﻻ نطيع فيكم أحدا أبدا
وإن قوتلتم لننصرنكم
Have you not observed the hypocrites who say to their friends among the People of the Scripture who disbelieve:
"If you are expelled, we indeed will go out with you, and we shall never obey anyone against you; and if you are attacked, we shall indeed help you.''
Allah then said,
والله يشهد إنهم لكاذبون
But Allah is Witness that they verily are liars.
meaning, the hypocrites lied when they issued this promise, because it was just words that they did not intend to fulfill