One night, after Allah Ta‘ala had fulfilled this desire by granting him ten sons, he was fast asleep in front of the Ka‘bah when he saw a person in a dream instructing him:

يا عبد المطلب أوف بنذرك لرب هذا البيت

“O ‘Abdul Muttalib! Fulfil your vow that you had pledged for the Lord of this sacred house.”

On awakening from this dream, ‘Abdul Muttalib summoned all his sons and revealed his vow and subsequent dream to them. They all submitted in one voice:

أوف بنذرك وافعل ما شئت

“Fulfil your vow and do as you please.”

(Extracted from Seeratul Mustafa 1/37)