Bukhari

Hadith Commentary:
If "kadhabu" is read with a lightened "dhal" (تخفیف ذال), then most likely the meaning would be that the prophets thought that all the promises Allah had made to them were false.
However, the well-known recitation is with the lightened form.
But its meaning is that the disbelievers thought that the promises made to the prophets regarding victory and help were all false, or the disbelievers thought that the promises the prophets had made to them were all false:
And al-Tabari chose the recitation with the lightened form and said: "I have chosen this because the verse occurs after His saying: 'So let them see how was the end of those before them,' so in that there is an indication that the despair of the messengers was regarding the faith of their people who denied them, so they were destroyed." (Fath al-Bari)
The summary of this statement is the same as mentioned above.
And reflect upon it, O people of understanding, so that you may comprehend.

Hadith Commentary:
1.
The well-known recitation is ﴿كُذِبُوا﴾ (with lightening/takhfif).
It is possible that this recitation did not reach Aisha (radi Allahu anha), and she, considering "zann" to mean certainty, denied this recitation.
According to her, the meaning of this recitation would be that the promises Allah made to those prophets were based on falsehood, and thus she rejected it.
Whereas, in the case of takhfif (lightening), the meaning is that the disbelievers thought that the promises of punishment made to them by the prophets had all turned out to be false and untrue.
In such circumstances, Allah’s help came to them.
2.
We have discussed this issue in detail under Surah al-Baqarah, verse: 214,
and Hadith: 4524.