Sahih Bukhari, Chapter: Characteristics of Prayer

Once Allah's Apostle delayed the 'Isha' prayer till 'Umar informed him that the women and children had slept. The Prophet came out and said, "None except you from amongst the dwellers of earth is waiting for this prayer." In those days, there was no prayer except in Medina and they used to pray the 'Isha' prayer between the disappearance of the twilight and the first third of the night.