From Sahih Muslim (Hadith 1463):
Sayyar b. Salama reported:I heard Abu Barza saying that the Messenger of Allah (ﷺ) did not mind some delay in the 'Isha' prayer even up to midnight and he did not like sleeping before (observing it) and talking after it. Shu'ba said: I again met him (Sayyar b. Salama) for the second time and he said: Even up to the third (part) of the night
Reference: Muslim 1463