Should a mother make a vow and pray for the healing of her sick 4-year-old son?

Supplicating for healing is among the best deeds, and Allah is the Healer who answers the distressed, just as He answered Ayyub (peace be upon him). Supplicating for the sick person is desirable, whereas making a vow is disliked, because it neither hastens nor postpones anything. Rather, it is used to extract from the miserly. Therefore, it is not recommended to make a vow; instead, one should supplicate and give charity, for the Prophet (peace and blessings of Allah be upon him) said: "Cure your sick ones with charity."