It is narrated from Sayyiduna Abdullah bin Mughaffal Muzani, may Allah be pleased with him, that the Prophet, peace and blessings be upon him, said: There is prayer between every two calls to prayer; whoever wishes may offer it.
Hadith Referenceمسند احمد / مسند المدنيين رضي الله عنهم اجمعين / 16790