פּירוש אויף בראשית 26:24

FEAR NOT, FOR I AM WITH THEE. Since Abimelech drove him away because of the Philistines’ jealousy of him, and since the herdsmen of Gerar quarrelled with him, Isaac feared lest they gather against him and smite him and his family. Therefore the Holy One, blessed be He, assured him that he should not fear them, and He blessed him. Then He prompted them so that the king went to Isaac with greater honor than that which he did to his father since he came with Phichol, the chief of his host, and also brought with him many of his friends.

וירא, this vision was meant to encourage Yitzchok not to be afraid on account of these territorial disputes over the sources of water for his flocks. He reassured him that those hating him now would not only give up their opposition but would come pleading for a peace-treaty with him; this is why He added that Yitzchok’s success would be linked to that of G’d’s servant Avraham. We see this promise fulfilled already in verse 26 when the King himself travels to see Yitzchok and is forced to acknowledge that the combination of Yitzchok’s G’d and Yitzchok is too powerful for him to oppose.

אל תירא, that they would reduce your heritage due to their constant interference with you.