Sahih Muslim Book 4, Hadith Number 1822.

Chapter : Do not get into the habit of observing prayer at the time of the rising sun and at the time of its setting.

Abdullah b. Mughaffal reported Allah’s Messenger (may peace be upon him) u saying: There Is between the two calls (Adhan and Iqama) a prayer. And he mentioned it three times, and at the third time he said: This applies to those who wish to do it.