At first...
At first, it says: “These are the towns some of whose tidings We recount unto you...” Then, the verse implies that it was not such that they became unnihilated without completing the argument, but surely their divine prophets went to them with clear evidences and those prophets tried their utmost effort to guide them.
The holy verse continues saying: “…and certainly their Messengers came to them with manifest proofs…” But they steadily showed opposition against the continuous preaches and repeated invitations of their prophets and persisted on their own saying. They were not ready to accept and believe in that which they had belied before.
Here is what the verse says: “…but they would not believe in what they had belied from before…” The cause of this obstinacy has been stated in the next sentence of the holy verse, as follows: “…Thus does Allah set a seal on the hearts of the infidels.” That is, those who step in the path of wrong, as a result of repetition and continuation of action, some corruptions such as perversion, infidelity, and impurity settle in their hearts so deeply that they remain fixed therein like the curvings upon a coin.
“And, We did not find in most of them any (firm) covenant, and verily We found most of them to be wrong-doers.”*** The objective meaning of the word ‘‘ ahd ’, (covenant), mentioned in the verse, is either the relation between Allah and the sound innate disposition of people, or the invitation and laws of prophets, or the special covenants which sometimes people made with prophets saying that, for example, if the prophet performed so and so as a miracle or solved a particular difficulty of theirs, they would believe.
One of the evidences of this kind in the Qur’ān is Surah’A‘rāf, No. 7, verses 134 and 135 which say: “And when the plague fell upon them, they said: ‘O’ Moses! invoke your Lord for us by the covenant He has made with you.