The Quran

لا يَستَوِي القاعِدونَ مِنَ المُؤمِنينَ غَيرُ أُولِي الضَّرَرِ وَالمُجاهِدونَ في سَبيلِ اللَّهِ بِأَموالِهِم وَأَنفُسِهِم ۚ فَضَّلَ اللَّهُ المُجاهِدينَ بِأَموالِهِم وَأَنفُسِهِم عَلَى القاعِدينَ دَرَجَةً ۚ وَكُلًّا وَعَدَ اللَّهُ الحُسنىٰ ۚ وَفَضَّلَ اللَّهُ المُجاهِدينَ عَلَى القاعِدينَ أَجرًا عَظيمًا

Muhammad Asad

SUCH of the believers as remain passive¹ - other than the disabled - cannot be deemed equal to those who strive hard in God's cause with their possessions and their lives:² God has exalted those who strive hard with their possessions and their lives far above those who remain passive. Although God has promised the ultimate good unto all [believers], yet has God exalted those who strive hard above those who remain passive by [promising them] a mighty reward -

Lit., "who sit [at home]"- i.e., who do not participate in the struggle in God's cause, be it physical or moral.
The term mujahid is derived from the verb jahada, which means "he struggled" or "strove hard" or "exerted himself", namely, in a good cause and against evil. Consequently, jihad denotes "striving in the cause of God" in the widest sense of this expression: that is to say, it applies not merely to physical warfare (qital) but to any righteous struggle in the moral sense as well; thus, for instance, the Prophet described man's struggle against his own passions and weaknesses (jihad an-nafs) as the "greatest jihad" (Bayhaqi, on the authority of Jabir ibn 'Abd Allah).