“Ahab was his close companion. He and Elijah came to inquire after the welfare of Hiel the Bethelite. He was sitting there and saying: Perhaps when Joshua pronounced his curse, this is what he cursed: that Jericho should not be rebuilt under another city’s name, nor another city under Jericho’s name. Elijah said to him: Yes. He said to him: Now, Moses’ curse is not being fulfilled, as it is written, ‘And you turn aside and serve other gods,’ and it is written, ‘Then the Lord’s anger will blaze against you, and He will shut up the heavens,’ and that man has established idolatry on every furrow and yet he does not let the rain go by without going to bow to it. Yet the curse of Joshua his disciple is fulfilled? Immediately, ‘And Elijah the Tishbite, of the settlers of Gilead, said: As the Lord, God of Israel, lives, there shall be neither dew nor rain…’ He prayed for mercy, and they gave him the key of rain, and he arose and went.”
Sanhedrin 113a.

The question is: if the Torah phrases it clearly that there will be no rain in a state of “if you do not listen,” why did rain fall in Ahab’s time, as emerges from the midrash? The question is more general regarding the paragraph of the Shema. Was there always a correlation between the spiritual state and the state of the rainfall?

A side question on the interpretive level: what did Elijah want to achieve with his decree?

In the Talmud this is presented as Moses’ curse and not the Holy One’s. It may be that this was his request, which the Holy One did not fulfill. And from this they make an a fortiori argument regarding Hiel. That is, the Holy One decided not to fulfill Moses’ curse. And perhaps this explains why there really is no correlation between keeping the commandments and rain, because this is only Moses’ curse and not a promise of the Torah.
However, there is a novelty here: that there are verses in the Torah that were said by Moses not in accordance with the Holy One’s view.
Elijah wanted to curse like Moses, since he too thought that idolatry deserves the punishment of drought. And it is interesting that the Holy One did fulfill his curse, unlike Moses’ and unlike Hiel’s. And perhaps that is because Hiel’s statement could have led to heresy.
It really is interesting that the Talmud itself says here that the Torah’s assurance is not fulfilled. This touches on all the arguments with me here on the site about the Torah’s promises and the Holy One’s involvement in the world.
However, according to my approach, there is a change in the Holy One’s policy, and over time He intervenes less and less. Until in our day it almost no longer happens. According to this, the Torah’s promises were said for their own time. And perhaps that is why they were not fulfilled in Ahab’s time.

To sum up, either way you take it, what comes out here is “heresy in a fundamental principle”: either there is a part of the Torah that was said by Moses not in accordance with the Holy One’s view, or there is a change in the Holy One’s policy in His providence over the world.