Imam Ja’fer As-Sadiq (pbuh) came up to talk to a man who was
busy working at constructing a window for his house.
After greeting him, Imam asked him why he needed a
window.
“Yabna Rasulillah! It is for light and fresh air that I am making
this window.”
Imam told him that if only his niyya had been to make a
window so that the sound of Adhan could be heard, he would
have not only got the benefit of light and fresh air but also the
thawab of having done something to bring him closer to
Allah. He would have converted a mubah act into a mustahab
one i.e. an allowable act into one that merits thawab.”
Excellent Stories Vol 1