(Refer to Silsilah Da'ifa; 6941)
"The Prophet informed us that we are only rewarded to the extent of our consciousness in prayer."
Please note that this is NOT a hadith of the Prophet peace be upon him and should not be attributed to him, but rather it is a statement of Sufyan Al-Thawri rahimahullah.
However, the following authentic hadith was narrated regarding perfecting our prayers such as having proper khushu' and concentration, as well as performing the actions of the prayer according to the sunnah, and that one's reward is in accordance to perfecting his prayer.
Ammar bin Yaasir radi Allahu anhu narrated that Prophet Muhammad sallahu alyihi wa sallam said, “One might finish the Salah, but only have a tenth, ninth, eighth, seventh, sixth, fifth, fourth, third, or half of it written for him” (Hasan, Sahih Abu Dawood; 796).