Is one who abandons reciting the Qur'an, remembering God, and performing the night prayer sinful because doing so causes sorcery to exhaust him and renders him unable to work?

There is no sin upon the bewitched person who is unable to recite [Qur'an] and perform standing [in prayer]. And he is hoped to be rewarded if his inability is due to illness. The Sunnah has indicated that the sick person is credited with the same reward as what he used to do when he was healthy and resident, as in the Hadith: "When a servant falls ill or travels, he is credited with the like of what he used to do when he was healthy and resident." This applies specifically to one who was performing an act of obedience and was then prevented from it, and whose intention was to continue performing it.