Sayyiduna Hasan (may Allah be pleased with him) says that (his uncle) Sayyiduna Aqil bin Abi Talib (may Allah be pleased with him) came to Basra and married a woman from Banu Jusham. According to custom, people congratulated him and said: «بالرفاء والبنين» (that is, congratulations on your marriage with hopes of goodness, blessing, harmony, affection, and sons). Upon this, he said: Do not say this; the Messenger of Allah (peace and blessings be upon him) forbade us from saying «بالرفاء و البنين» and instructed us to say: «بَارَكَاللّٰهُلَكَوَبَارَكَعَلَيْكَ», meaning "May Allah bless you and may blessing be upon you."
Hadith Referenceسنن دارمي / من كتاب النكاح / 2210
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):في القلب ميل إلى تصحيح هذا الإسناد، [مكتبه الشامله نمبر: 2219]
Hadith Takhrijیہ روایت دوسری اسانید سے صحیح ہے۔ دیکھئے: [ترمذي 3371] ، [ابن ماجه 1906] ، [ابن السني فى عمل اليوم و الليلة 602] ، [النسائي فى الكبرى 10092] ، [طبراني فى الكبير 193/17، 512، 517، 518]
Brief Explanation
(Commentary on Hadith 2209)
«الرِّفَاءِوَالْبَنِيْنَ» Saying this for the groom was also not something particularly bad, but since it implied that the birth of daughters was not liked by them, for this reason it was prohibited. In any case, after marriage, saying «بَارَكَاللّٰهُلَكَوَبَارَكَعَلَيْكَوَجَمَعَبَيْنَكُمَافِيخَيْر» for the groom is itself Sunnah, as will be mentioned later.