58
Nawawi says in Rawdah at-Taalibeen (1/224
published by Maktab al-Islami):
"The
intention is the purpose, so the person
about to pray brings to mind that prayer
and what is relevant of its characteristics,
such as which prayer it is, whether it
is obligatory etc. & he brings these
things together in his intention with
the first takbeer."
59
Bukhaari, Muslim and others. It is given
in Irwaa' (no. 22)