Aruch HaShulchan 251:3

The Tur wrote in the name of Rav Saadia Gaon: One is obligated to prioritize one’s own livelihood before any other person, and one is not obligated to give tzedakah until one has a livelihood, as it says “And your fellow shall live with you” - your life precedes the life of your fellow. And thus the Tzarfatit [widow] to Eliyahu “Prepare it for me and my son.” (Kings I, 17:12) And after you ensure your own livelihood, then you should prioritize the livelihood of your parents over your children, and then prioritize your children - until here are his words. And our rabbi the Rama (Rav Moshe Isserles) copied this and said “You prioritize your own life first,” etc. If your parents are poor, they precede the livelihood of your children, and your children precede your siblings, and they precede the rest of your relatives, and your relatives precede your neighbors, and your neighbors precede your townspeople, and your townspeople precede those of another city, and this is the law also if they are captives and you have to redeem them - until here are his words. [Translation by AJWS]