Sayyiduna Uqbah bin Amir (may Allah be pleased with him) said: There was the duty of tending the camels, and when my turn came I kept grazing them, then I brought them back in the evening. Meanwhile I found the Messenger of Allah (peace and blessings be upon him) standing and speaking to the people, and I caught this part of his speech: "There is none of you who performs ablution (wudu) and performs his ablution well, then stands and prays two rak'ahs, turning to them with full attention with his face and his heart, except that Paradise becomes binding for him."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14988