To invoke for increase of offspring, along with His Blessings.

Narrated Anas:

Um Sulaim said (to the Prophet), "Anas is your servant;
so please invoke for Allah's blessings for him." He said "O Allah! Increase his wealth and offspring, and Bless (for him) whatever You give him."

حَدَّثَنَا أَبُو زَيْدٍ، سَعِيدُ بْنُ الرَّبِيعِ حَدَّثَنَا شُعْبَةُ، عَنْ قَتَادَةَ، قَالَ سَمِعْتُ أَنَسًا ـ رضى الله عنه ـ قَالَ قَالَتْ أُمُّ سُلَيْمٍ أَنَسٌ خَادِمُكَ. قَالَ " اللَّهُمَّ أَكْثِرْ مَالَهُ وَوَلَدَهُ، وَبَارِكْ لَهُ فِيمَا أَعْطَيْتَهُ ".