Ali bin Rabi'ah (may Allah have mercy on him) said: We went with Ali bin Abi Talib (may Allah be pleased with him) towards Syria. He led us in two rak'ahs each (for every prayer) until our return. When we came back and caught sight of Kufah, the time of prayer also arrived, so they said: "O Commander of the Believers! This is Kufah; shall we complete the prayer?" He said: "No, not until you have entered it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5448