((بَارَكَ اللَّهُ لَكَ فِي الْمَوْهُوبِ لَكَ، وَشَكَرْتَ الْوَاهِبَ، وَبَلَغَ أَشُدَّهُ، وَرُزِقْتَ بِرَّهُ)). وَيَرُدُّ عَلَيْهِ الْمُهَــــــنَّأُ فَيَقُولُ: ((بَارَكَ اللَّهُ لَكَ وَبَارَكَ عَلَيْكَ، وَجَزَاكَ اللَّهُ خَيْراً، وَرَزَقَكَ اللَّهُ مِثْلَهُ، وَأَجْزَلَ ثَوَابَكَ)).
Transliteration
Baarakallaahu laka fil-mawhoobi laka, wa shakartal-waahiba, wa balagha 'ashuddahu, wa ruzigta birrahu. The reply of the person being congratulated is to say: Baarakallahu laka wa baaraka 'alayka, wa jazaakallaahu khayran, wa razaqakallaahu mithlahu, wa 'ajzala thawaabaka.
Translation
May Allah bless you with His gift to you and may you (the new parent) give thanks, may the child reach the maturity of years, and may you be granted its righteousness. The reply of the person being congratulated is to say: May Allah bless you, and shower His blessings upon you, and may Allah reward you well and bestow upon you its like and reward you abundantly
Source
Hisnul Muslim (Fortress of the Muslim), No. 145 — chapter “Congratulations for new parents and how they should respond”. hisnmuslim.com
Related Duas
كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُعَوِّذُ الحَسَنَ وَالحُسَينَ رضي الله عنهما ((أُعِيذُكُمَا بِكَلِمَاتِ اللَّهِ التَّامَّةِ مِنْ كُلِّ شَيْطَانٍ وَهَامَّةٍ، وَمِنْ كُلِّ عَيْنٍ لاَمَّةٍ)).
(Ibn AAabbas related that the Messenger of Allah used to commend Al-Hasan and Al-Husayn to Allah’s protection, saying:(I commend you two to the protection of Allah’s perfect words from every devil, vermin, and every evil…
Hisnul Muslim · No. 146