Musannaf Ibn Abi Shayba 3:5395

Jarir narrated to us, from Mansur, from Numayr ibn Salamah, who said: The first thing the servant will be asked about, he will be asked about his prayer. If it is accepted from him, the rest of his deeds will be accepted from him. And if it is rejected against him, the rest of his deeds will be rejected against him.