The word «سامر» which is in the Quran is derived from «سمر» . Its plural is «سمار» , and the word «سامر» in this verse is in the meaning of plural. «سمر» originally refers to the light of the moon; the Arabs used to converse and chat during moonlit nights.

Narrated Abu-l-Minhal: My father and I went to Abi Barza Al-Aslami and my father said to him, "Tell us how Allah's Apostle used to offer the compulsory congregational prayers." He said, "He used to pray the Zuhr prayer, which you call the first prayer, as the sun declined at noon, the `Asr at a time when one of US could go to his family at the farthest place in Medina while the sun was still hot. (The narrator forgot what Abu Barza had said about the Maghrib prayer), and the Prophet preferred to pray the `Isha' late and disliked to sleep before it or talk after it. And he used to return after finishing the morning prayer at such a time when it was possible for one to recognize the person sitting by his side and he (the Prophet) used to recite 60 to 100 'Ayat' (verses) of the Qur'an in it."