There is a detail: If the forgetful person has the ability to fast, like a strong young man, he must be reminded, and it is strictly disliked not to remind him. If he does not have the strength, it is preferable not to remind him, as it may disrupt his livelihood and kindness towards him, whether he is an old man or a young man, as mentioned in Al-Hadiyah Al-‘Alaiyah, page 160, and in Radd al-Muhtar, volume 2, page 97.