Explanation of the words of Imam al-Nawawi (may Allah have mercy on him) regarding what he quoted: "

The Shaykh : In the name of Allah, the Most Gracious, the Most Merciful.
Praise be to Allah, Lord of the worlds, and blessings and peace be upon our Prophet Muhammad, and upon his family and his Companions, and those who follow them with excellence until the Day of Judgment.
The author (may Allah have mercy on him) mentioned this hadith in the chapter on moderation in worship: This vow included things that are beloved to Allah (Mighty and Majestic) and things that are not beloved. As for what is beloved to Allah, it is fasting, because fasting is an act of worship. The Prophet (peace and blessings be upon him) said: As for his standing in the sun without seeking shade, and his not speaking, this is not beloved to Allah (Mighty and Majestic); it is not beloved to Allah. Therefore, the Prophet (peace and blessings be upon him) ordered this man to leave what he vowed, and let him know that the original ruling on a vow is disliked. In fact, some scholars said: It is forbidden, and it is not permissible for a person to make a vow, because when a person makes a vow, he burdens himself with what Allah has not burdened him with. For this reason, But if it happens that a person makes a vow, vows are divided into categories: one category has the ruling of an oath, another category is a vow of disobedience, and a third category is a vow of obedience. As for the one that has the ruling of an oath, it is the one in which the person intended to emphasize a matter, whether by negation or affirmation, or by verification or refutation. That is, he intended to emphasize it. For example, if it is said to a man: "You told us such and such, but you did not tell the truth," and he says: "If I am lying, I have a vow upon me to Allah to fast for a year," there is no doubt that his purpose is to emphasize his statement so that people will believe him. Its ruling is the ruling of an oath because he intended to emphasize what he said. Likewise, if he intends to urge himself, such as saying: "If I do not do such and such, I have a vow upon me to Allah to fast for a year," this is also intended to urge himself to do what was mentioned, and its ruling is also the ruling of an oath. The evidence for this is the saying of the Prophet (peace and blessings be upon him): And this person intended an oath, so he has what he intended. As for the second category, it is the forbidden one. If a person makes a forbidden vow, it is forbidden for him to fulfill it. For example, if he says: "I have a vow upon me to Allah to drink intoxicants, may Allah protect us from that," this is a forbidden vow, so it is not permissible for him to drink intoxicants, but he must pay the expiation for an oath according to the stronger opinion. Even though some scholars said: There is nothing upon him because it is a vow that did not take effect. But the correct view is that it is a vow that took effect, but it is not permissible to fulfill it. Similarly, if a woman says: "I have a vow upon me to Allah to fast the days of my menstruation," this is forbidden, and it is not permissible for her to fast during menstruation, and she must pay the expiation for an oath. As for the third category: it is the vow of obedience, where a person makes a vow of obedience, such as saying: "I have a vow upon me to Allah to fast the white days, which are the thirteenth, fourteenth, and fifteenth." He is obligated to fulfill his vow because of the saying of the Prophet (peace and blessings be upon him): Or he says: "I have a vow upon me to Allah to pray two rak'ahs in the Duha prayer." He is obligated to fulfill his vow because it is obedience. The Prophet (peace and blessings be upon him) said: If his vow includes both obedience and non-obedience, he must fulfill the obedience, and he does not fulfill the non-obedience, and he pays the expiation for an oath. For example, the story of this man who vowed to stand in the sun, not to seek shade, not to speak, and to fast. The Prophet (peace and blessings be upon him) ordered him to fast because it is obedience, but regarding standing, not seeking shade, and not speaking, he said: Many people today, when they find a matter difficult or fear for it, make a vow. For example, many people, when someone is ill, say: "I have a vow upon me to Allah that if He heals my sick one, I will do such and such." This is prohibited; it is prohibited either as a prohibition of disliking or a prohibition of forbiddance. Ask Allah for health for your sick one without a vow. But if we assume that he vowed that if Allah heals his sick one, he will do such and such, and Allah healed him, he is obligated to fulfill the vow. And success is from Allah.