Strength of Body, Strength of Heart
Imām Ibn Taimiyyah, may Allāh have mercy on him, said: “One of the Salaf [the righteous, first three generations of this ummah] said:
A believer’s strength is in his heart [while] his weakness is in his body; a hypocrite’s strength is in his body [while] his weakness is in his heart.
Majmūʿ Al-Fatāwá, vol. 2, p. 395.