Albert Barnes Commentary 1 Samuel 25:40

"And when the servants of David were come to Abigail to Carmel, they spake unto her, saying, David hath sent us unto thee, to take thee to him to wife." — 1 Samuel 25:40 (ASV)

There is no record of the exact time that passed between Nabal’s death and David hearing of it, or again, between his hearing of it and his message to Abigail; nor is there any reason to suppose that the marriage took place with improper haste. The widow of a husband such as Nabal could not, however, be expected to revere his memory. After the usual seven days of mourning, she would probably feel free to act as custom allowed (see 2 Samuel 11:26).