It is narrated from Sayyiduna Abu Musa (may Allah be pleased with him) that a questioner asked the Prophet (peace and blessings be upon him) a question, and he (peace and blessings be upon him) gave him no answer; then he ordered Bilal (may Allah be pleased with him), and he called the iqamah, and he mentioned the hadith. In it is: he ordered Bilal (may Allah be pleased with him), and he called the iqamah for Isha when the redness had disappeared; then when the next day came, and he mentioned the hadith. In it is: he led the Isha prayer up to a third of the night, then he said: "Where is the one who asked about the times of the prayer? The time is between these two."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1750