Here the words "hearts" and "souls" have similar meanings. Together they emphasize deep personal knowledge. (See: [[rc://en/ta/man/translate/figs-doublet]])
These words emphasize that Yahweh's promises have all occurred. This can be stated in positive form. AT: "every word has come true" (See: [[rc://en/ta/man/translate/figs-doublenegatives]] and [[rc://en/ta/man/translate/figs-parallelism]])