The infallible Imams have taught us to act moderately in worshiping. It is not necessary to be awake all night busy worshiping and saying prayers, or it is not needed to say three hundred units of prayers during the day and night, this is an oppression against oneself. Moreover, saying the afternoon and evening prayers must not last about two hours. Saying prayers must be done in a usual way but with full attention and presence of heart. In fact, in saying prayers what matters is its quality not its quantity.
source : erfan.ir
