Abū Hurayrah reports that RasūlAllāh şallAllāhu álayhi wa sallam said:
 
The beauty of a man’s Islam is that he renounces that which concerns him not.
min ĥusni islāmi’l mar’yi tarkuhu mā lā yá-nīh
Tirmidhi 2318 (Ĥasan)
 

Abū Yaálā Shaddād ibn al-Auws reports from RasūlAllāh şallAllāhu álayhi wa sallam that he said:
 
Wise is he who checks his nafs [desires] and works for [his life] after death. And feeble [and unwise] is he who follows his nafs and its desires [wantonly], but yet hopes [for a reward] from Allāh.
al-kayyisu man dāna nafsahu wa ámila limā baáda’l mawt. wa'l áājizu man atba-á nafsahu hawāhā wa tamannā ál’Allāh
Tirmidhi 2459 (Ĥasan)