Aishah ( ﺭﺿﻲ ﺍﻟﻠﻪ ﻋﻨﺎ ) narrated that the Prophet ﷺ entered upon her one day and saw a small piece of bread on the floor, so he picked it up and wiped it, then told her: “O Aishah ( ﺭﺿﻲ ﺍﻟﻠﻪ ﻋﻨﺎ ), treat the blessings of Allah with respect, for if it departs from a household it may never come back to them.” [Ibn Abi-Dunya]
Seeing a small piece of bread on the floor made the Prophet ﷺ warn Aishah (ﺭﺿﻲ ﺍﻟﻠﻪ ﻋﻨﺎ ) regarding being ungrateful to Allah ( ﺳﺒﺤﺎﻧﻪ ﻭ ﺗﻌﺎﻟﻰ ). What would he have said were he to see how plates full of food are thrown away in trash cans today.
Parents take their children to others’ houses, put food on their plates and say nothing to them when they remorselessly leave it to be thrown away. These are the very same people who you will see complaining about not having enough.
Imam Al-Hasan Al-Basree ( ﺭﺿﻲ ﺍﻟﻠﻪ ﻋﻨﻪ ) said:
“We laugh and yet who knows? Perhaps Allah has looked at some of our works and said: ‘I will not accept anything from you.’ Woe to you, son of Adam! Can you fight Allah? Whoever disobeys Allah is fighting Him. By Allah! I have met seventy veterans of Badr. Most of their garments were wool. Had you seen them you would have said they are crazy, and had they seen the best among you they would have said: ‘Those people will have no part in the Hereafter.’ Had they seen the worst among you they would have said: ‘Those people do not believe in the Day of Reckoning.’ I have seen people for whom this world was cheaper than the dust under their feet. I have seen people the like of whom would come home at night, not finding more than his own portion of food, and yet say: ‘I shall not put all of this into my belly. I shall certainly give some away for Allah’s sake.’ Then he would give away some of his food in charity, even if he were more in need of it than its recipient.”
[Hilyah al-Awliya wa Tabaqat al-Asfiya 2/134]