1. offer prayers perfectly
2. pay the Zakat (obligatory charity)
3. and be sincere and true to every Muslim.
In-book : Book 2, Hadith 50
USC-MSA web (English) : Vol. 1, Book 2, Hadith 55 (deprecated)
2. Belief
باب إِذَا حَضَرَ الطَّعَامُ وَأُقِيمَتِ الصَّلاَةُ