''We do not inherit the earth from our ancestors; we borrow it from our children."
Earth is Allah's (SWT) creation, so who are we to trash it? Allah (SWT) tells us
"Greater indeed than the creation of man is the creation of the heavens and the earth." (40:57).
As muslims it is our duty to care for the earth for our sake and the sake of our children. It houses bountiful signs of Allah's (SWT) indefinite power.
The Prophet Muhammed (SAW) once told his followers that they would be rewarded if they cared for the earth. He said
"If any Muslim plants any plant and a human being or an animal eats of it, he will be rewarded as if he had given that much in charity." (Sahih Al-Bukhari, 8:41)
Another tradition of the Prophet Muhammad, or hadith, quotes him as saying:
"If the Hour (Judgment Day) is about to be established and one of you is holding a palm shoot, let him take advantage of even one second before the Hour is established to plant it."
Think 'bout that the next time you litter!