Ibn Abi Layla narrates from Sayyiduna Umar (may Allah be pleased with him): "The Friday prayer is two rak'ahs, the prayer of Eid al-Adha is two rak'ahs, and the traveller's prayer is two rak'ahs; these are complete, not shortened. This is from the blessed tongue of your Prophet (peace and blessings be upon him)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5719