T is 20 years old, his parents immigrated from Bangladesh, he was born in Sylmar, California. He told me about this belief about why you should cover your food if you walk away from your plate.
“Whenever you have food out… if you walk away from your food… basically the devil is spitting on your food, so you always need to cover your food. This is a Muslim, Islamic tradition… and you do it whenever you’re eating but also during Ramadan, which is the month of fasting, we break our fast when the sun sets, right… so what we do is we set the table with the food we’re gonna break our fast with… so we do our prayers before we eat while the sun is setting… so we break our fast with a date and some water and then we go pray formally… because we have to pray five times a day… so we say one of the five prayers and we have to cover our food and after we finish with the prayer then we can eat.”
This website explains the hadith, or statement from the prophet, of covering food, https://www.understanding-islam.com/hadith-regarding-covering-food-during-the-night/, stating that covering food is to avoid disease. The link between the devil’s spit and pestilence is straightforward. For general information about spitting and the devil in Islam, see https://www.opindia.com/2021/03/the-significance-of-spitting-in-islam-how-spitting-can-ward-off-satan/