Ruth 4:15

“ And he will be to you a restorer of life, and a nourisher of your old age, for your daughter-in-law, who loves you, who is better to you than seven sons, has borne him.”

And they assured Naomi that once he was old enough he would ‘restore her life' by giving her encouragement and a reason for living. And secondly that he would be a ‘nourisher of her old age', ensuring that she was provided for and that all her needs were met. So the woman who had left Moab in such despair was now assured of a safe and happy future. And this was because her own daughter-in-law had borne him, a daughter-in-law who loved her and had indeed been better to her than seven sons, seven indicating the divinely perfect number. To have seven sons would be the ideal, giving total confidence and provision for the future, and the idea here is thus that Ruth was such a wonderful daughter-in-law that she was of greater value than seven sons, because Naomi could have such confidence in her. Brought up under such a mother, they are saying, how could the son not be similar?