Between faith and prayer

'Is there anything more important than prayer?' a disciple asked his teacher.
The teacher told the disciple to go to a nearby tree and cut off a branch. The disciple obeyed.
'Is the tree still alive?' asked the teacher.
'As alive as it was before.'
'Then go over there and slice through its roots.'
'If I do that, the tree will die.'
'Prayers are the branches of a tree whose roots are called Faith,' said the teacher. 'Faith can exist without prayer, but prayer cannot exist without faith.'