It is narrated from Aishah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: "Your children are a gift from Allah to you: 'He grants females to whom He wills, and grants males to whom He wills' [Surah al-Shura: 49]. So they and their wealth are yours when you are in need of it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النفقات / 15745