John Gill Commentary 1 Samuel 25:28

"Forgive, I pray thee, the trespass of thy handmaid: for Jehovah will certainly make my lord a sure house, because my lord fighteth the battles of Jehovah; and evil shall not be found in thee all thy days." — 1 Samuel 25:28 (ASV)

I pray you, forgive the trespass of your handmaid
The trespasses, as the Targum, either the sin of her husband, she had taken upon herself, or her boldness in troubling him with her petitions and solicitations, and even with the present she had brought:

for the Lord will certainly make my lord a sure house ;
or a firm kingdom, as the Targum; would raise him to the kingdom of Israel, and establish it in his posterity, that it should not be taken from him, as it would be from Saul:

because my lord fighteth the battles of the Lord ;
the battles of the people of the Lord, as the Targum, of the people of Israel against the Philistines; which he had often done with success, the Lord being with him, and prospering him and therefore would firmly settle him on the throne, and continue the kingdom in his posterity:

and evil has not been found in you [all] your days ;
no unjust action had been committed by him against his king and country, however he had been reproached and calumniated; and she hoped that therefore none would be done by him now to stain so fair a character.