Musannaf Ibn Abi Shayba 38:108

Ibn Fudayl narrated to us, from ‘Ata’ ibn al-Sa’ib, who said: More than one person narrated to me that a judge from the judges of al-Sham came to ‘Umar and said: "O Commander of the Faithful, I saw a vision that terrified me." He asked: "What is it?" He replied: "I saw the sun and the moon fighting, and the stars were with them, divided into two halves." He asked: "With which of the two were you?" He replied: "I was with the moon against the sun." ‘Umar said: "‘And We have made the night and the day as two signs, so We erased the sign of the night and made the sign of the day visible.’ Go, for by Allah, you shall never work for me again." ‘Ata’ said: It reached me that he was killed alongside Mu’awiyah on the day of Siffin.