Abd al-Malik, the son of Sayyiduna Ka'b bin Ujrah (may Allah be pleased with him), said: On the day of Eid I went out with Sayyiduna Ka'b bin Ujrah (may Allah be pleased with him) to the Eid prayer ground. He sat down (at the prayer ground) before the imam came and did not pray until the imam had left, while the people were going towards the mosque in rows upon rows. I said: Do you not see? He said: "This is an innovation and an abandonment of the Sunnah."
Hadith Referenceالمعجم الكبير للطبراني / باب الكاف / 16375