Is the deceased man, who bequeathed the Hajj but whose will was not executed, absolved, and is there a sin for not executing it?

The majority of scholars are of the opinion that Hajj is an immediate obligation for whoever is able, and delaying it without a valid excuse is a sin. If a capable person dies before performing Hajj, their responsibility remains. Their heirs must perform Hajj on their behalf from their wealth, whether they bequeathed it or not. The sin of not performing Hajj on their behalf falls upon the heirs, and the obligation is not lifted from the deceased except by its performance on their behalf.