Four things ruin the body: anxiety, grief, hunger, sleeplessness. And four things bring joy to the body: looking at greenery, at running water, at the beloved, and at fruits.
Four darken the sight: walking barefoot; keeping company with one hated, or disliked, or an enemy; excessive weeping; and too much looking at fine script.
Four strengthen the body: wearing soft clothes; taking a moderate bath; eating sweet and fatty food; and smelling sweet scents.
Four darken the face and conceal its honour, its beauty and its radiance: lying; insolence; arguing without knowledge; and indulging in immorality. Four illuminate the face and increase its dignity: chivalry; loyalty; generosity; and piety; and four bring on hatred and loathing: pride; envy; lying; and slander.
Four bring one’s sustenance: standing for prayer at night; asking forgiveness before dawn; habitual almsgiving; and remembrance of God at the beginning and end of the night. And four prevent sustenance: sleep in the morning; insufficient worship; laziness; and treachery.
Four harm the understanding and intelligence: excessive eating of sour foods and of fruits; sleeping upon the nape of the neck; anxiety; and worry. And four increase the intellect: protecting the heart (from distractions); reducing intake of food and drink; careful organisation of the diet with sweet and fatty things; and expulsion of superfluities which make the body heavy.
Ibn Qayyim al-Jawzia (d. 715/1350), Medicine of the Prophet (al-Tibb al-Nabawi), trans. by Penelope Johnstone (Cambridge: Islamic Texts Society, 1996), 286-287.