Sunnan Abu Dawud Collection: ::Book Number 19:: Hadith # 3020
Narrated Uthman ibn Abul'As: When the deputation of Thaqif came to the Apostle of Allah (peace_be_upon_him), he made them stay in the mosque, so that it might soften their hearts. They stipulated to him that they would not be called to participate in Jihad, to pay zakat and to offer prayer. The Apostle of Allah (peace_be_upon_him) said: You may have the concession that you will not be called to participate in jihad and pay zakat, but there is no good in a religion which has no bowing (i.e. prayer).