There is an interesting parallel between the story of King David and Avigail and Avraham and Yitzchak. This is brought by Rabbeinu Bechaye.
Yitzchak’s lineage was questioned, as many suspected that it was Avimelech who fathered Yitzchak. In order to remove these rumors, Hashem caused Avraham and Yitzchak to look identical.
King David had a run in with Naval, husband of Avigail. After he died on Yom Kippur, David took Avigail as his wife. Although he waited three months, because Avigail conceived immediately, many spoke badly about David and accused Avigail of having conceived from slaves.
In this incident as well, the son born, Kilav, looked exactly like David.
History repeats itself and Hashem always comes to the aid of צדיקים. Shabbat Shalom