“have them ritually cleansed.” More literally, “make them holy.” It is unclear exactly why Job would do this or see the need to do this; the laws of clean and unclean, and exactly what was considered to be sin at this time and in that culture are unclear. Job was not part of Abraham’s lineage and was not a part of Israel (there was no “Israel” when Job lived). Job apparently did this as part of his obligation as the family priest and only because he thought his children might have sinned.
“he rose up early in the morning.” This is an idiom, and refers to doing something diligently and over and over. It might well be understood as, “Job diligently and regularly offered burnt offerings” for them.
“cursed God.” The Hebrew is literally “blessed God,” but the term “blessed” is used euphemistically for “curse,” both here, Job 1:11; 2:5 and other places in the Bible (see commentary on 1 Kings 21:10).
“in their hearts.” In this context, the phrase “in their hearts” can also mean “in their thoughts” (see commentary on Prov. 15:21).
“regularly.” The Hebrew is literally, “all the days,” that is, all the days he thought it necessary, and thus he did it regularly.