10 Hashem saw what they did, how they were turning back from their evil ways. And Hashem renounced the punishment He had planned to bring upon them, and did not carry it out.
va-YAR ha-e-lo-HEEM et ma-a-say-HEM kee SHA-vu mi-dar-KAM ha-ra-AH va-yi-NA-khem ha-e-lo-HEEM al ha-ra-AH a-sher di-BER la-a-sot la-HEM v’-LO a-SAH
י וַיַּרְא הָאֱלֹהִים אֶת־מַעֲשֵׂיהֶם כִּי־שָׁבוּ מִדַּרְכָּם הָרָעָה וַיִּנָּחֶם הָאֱלֹהִים עַל־הָרָעָה אֲשֶׁר־דִּבֶּר לַעֲשׂוֹת־לָהֶם וְלֹא עָשָׂה׃
3:10 How they were turning back from their evil ways
The people of Nineveh don sackcloth, fast, and sit in dust and ashes, in the hope that this will bring Hashem to forgive them. What Yona teaches us, however, is that it is not these external actions that bring about their forgiveness. Instead, what impresses Hashem is the fact that these actions reflected, and perhaps helped bring about, a fundamental change in their mentality. They abandon their evil ways and make a true commitment to behave righteously and justly in the future. Without such a genuine change of heart, the external signs remain empty gestures. The Sages of the Talmud (Taanit 16a) derive this lesson from the fact that the verse does not say “God saw their sackcloth and fasting,” but rather, “Hashem saw what they did, how they were turning back from their evil ways”.