What is "mi'Kedem la'Ir", and why did he go to there?
Radak: It is east of the city. He went until he will see - perhaps they will not persist in their Teshuvah, and the decree will return to them 1 . He stood there until the 40 days were finished.
Malbim: It is east of the city. He thought that even if there will not be a general destruction, perhaps there will be some impression, and some evil will occur. Regarding Chet ha'Egel, it says "va'Yinachem Hashem Al ha'Ra'ah" (Shemos 32:14), and even so He sent a plague on the nation that made the Egel.
Even though Radak (1) said that Hashem told him that He retracted from His decree, perhaps He would return it if they return to their evil way. (PF)