Is acknowledgment required when responding to congratulations or blessings regarding offspring?
General Chapter
Al-Mughni
Book of Mutual Imprecation (Li'an)
Primary text
If a person is congratulated concerning offspring and responds by saying "Aamna 'ala ad-du'a" (I concur with the supplication), it becomes obligatory for the child to be legally attributed to him. This is the position held by all scholars. Similarly, if the husband states, "Ahsana Allahu jaza'ak" (May Allah reward you well), or "Baraka Allahu 'alayk" (May Allah bless you), or "Razaqak Allahu mithlahu" (May Allah grant you its like), the attribution of the child is obligatory. This is the opinion of Abu Hanifa. The evidence is that such responses are customarily interpreted as acceptance in such matters, thus functioning as an admission, similar to affirming the prayer.
Supporting text
Al-Shafi'i holds that the attribution is not obligatory because the husband is merely acknowledging the good intent of the greeter. He argues that saying 'May Allah grant you its like' is neither an admission nor does it necessarily imply one. Furthermore, if the husband remains silent, some scholars, like Abu Bakr, hold that silence constitutes an admission because silence functions as a resolution indicating acceptance in the case of a virgin and in other contexts, making it applicable here as well.