Sahih Bukhari Volume 002, Book 021, Hadith Number 278.
Narated By Marthad bin 'Abdullah Al-Yazani : I went to 'Uqba bin 'Amir Al-Juhani and said, "Is it not surprising that Abi Tamim offers two Rakat before the Maghrib prayer?" 'Uqba said, "We used to do so in the life-time of Allah's Apostle." I asked him, "What prevents you from offering it now?" He replied, "Business."