Sahih Muslim
The Book of Faith (Kitab Al-Iman)
Book Number: 001 / Hadith Number: 152
'Abdullah b. Mas'ud reported: I said: Messenger of Allah, which of the deeds (takes one) nearer to Paradise? He (the Holy Prophet) replied: Prayer at its proper time, I said: What next, Messenger of Allah? He replied: Kindness to the parents. I said: What next? He replied: Jihad in the cause of Allah.