My mum said to eat all of a chapati as it would do dua for me or say or on judgement day i didnt waste it and i covered it when not eating it - is this a bidah or anything i cant find anything online

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

We do not know of any authentic religious evidence supporting the claim that when one eats food, be it chapati or any other food, the food supplicates Allaah on his behalf. However, it has been reported that the food seeks forgiveness for the person after he eats it. Nubayshah Al-Huthali narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said: "Whoever eats from a bowl then licks it clean, the bowl will pray for forgiveness for him." [At-Tirmithi and Ibn Maajah] Al-Albaani classified it as weak in Dha‘eef At-Tirmithi and Dha‘eef Ibn Maajah.

Authentic Ahaadeeth have been reported about the stomach being the worst container to fill, and urging Muslims to eat only what sustains themselves and to avoid overeating. If a Muslim wishes to eat anything more than that, he should leave one-third of his stomach for his breath. The Prophet, sallallaahu ‘alayhi wa sallam, said: "No man fills a container worse than his stomach. A few morsels that keep his back upright (i.e. satisfy one's hunger and sustain him) are sufficient for him. If he must, then he should keep one-third for food, one-third for drink, and one-third for his breathing." [At-Tirmithi]

Tuhfat Al-Ahwathi reads: "One-third for his breathing means that one should leave one third (of his stomach) to be able to breathe and to have a lean and light body. This is the proper limit within what is permissible in this regard. It is prohibited to eat beyond the point of fullness and satisfaction of hunger. At-Teeybi wrote, 'It means that it is obligatory for a Muslim to avoid overeating and to eat only what satisfies his hunger and sustains his life so as to be able to perform acts of obedience to Allaah. If he wants to eat more than that, he should not exceed that limit underlined in the Hadeeth (i.e. one-third).'" [End of quote]

Hence, you are advised to eat moderately and abide by the advice of the Prophet, sallallaahu ‘alayhi wa sallam, for it is certainly more beneficial to you than your mother's advice. You are also advised not to throw away the leftover food because this consists in squandering one's wealth wastefully, which the Prophet, sallallaahu ‘alayhi wa sallam, has prohibited. You can give the leftover food to the poor and needy or keep it for another meal. It should not be thrown away unless it is feared to cause harm to the body if consumed or it is no longer good. It may also be served to animals; feeding animals is a rewardable righteous act. It has been reported that people asked, "O Messenger of Allaah, is there a reward for us in feeding animals?" He, sallallaahu ‘alayhi wa sallam, replied, "Yes, there is a reward for feeding any living being." [Al-Bukhari and Muslim] If there are no animals to serve the leftover food, then we believe that there would be no harm in throwing it away.

However, if your mother tells you to eat your whole meal and you fear being undutiful if you do not, then you should obey her and eat the amount that would not cause harm to your body or consist in overeating; obedience to one's mother is obligatory in what does not consist in disobedience to Allaah, and eating to the extent of incurring harm on the body or overeating is disliked, as stated in Manaar As-Sabeel: "It is disliked to overeat to the extent of causing harm to oneself; eating until one is full is permissible only if it does not incur any harm. Al-Iqnaa‘ reads: 'If it is feared that eating until one is full will cause harm on the body or lead to indigestion, it is prohibited.'" [End of quote]

When one is left with two possible options, either to do what is disliked or neglect what is obligatory, then doing what is obligatory takes precedence. For further benefit, please refer to Fatwa 88435 about eating in moderation and avoiding wasting food.

Allaah Knows best.