What did the Prophet intend by his saying: "And whoever is unable, then let him fast, for it is a Wija’ for him," and does this mean that fasting is obligatory until marriage?

The Prophet, peace and blessings be upon him, guided young people towards marriage as a means of preserving their chastity, safeguarding their private parts, and lowering their gaze from the forbidden. He also guided those unable to marry to fasting as a way to curb the intensity of desire. Scholars differed on the meaning of "al-ba'ah" in the hadith. Some said it refers to intercourse and its expenses, while others said it refers to the expenses of marriage. Fasting in this hadith is not obligatory. If you are able to marry, then hasten to do so. If you are not able, then practice self-restraint until you are able, and increase in fasting while safeguarding your hearing and sight from the forbidden.