Al-Hakim al-Tirmidhi (d. c. 932 CE, though sources differ on the date) was a scholar of Tirmidh in Central Asia, known for his writings on the heart, the self and the inner meanings of worship.
Islam Central has 3 summaries of works by al-Hakim al-Tirmidhi, each in short audio and text chapters with a free preview on its page.

Al-Hakim al-Tirmidhi on training the self: trusting Allah over provision, moving from patience to contentment, weaning the soul from desire, and polishing the heart until certainty shines.
12 chapters · 34 min
Al-Hakim al-Tirmidhi's parables from the Qur'an, the Prophet and his own reflection: the lamp in the niche, the citron and the colocynth, the man who sold his house, the runaway servants and the three wineskins.
13 chapters · 37 min
Al-Hakim al-Tirmidhi pictures reason and desire as two sides, each with fifty helpers, and explains reason's helpers one by one: understanding, insight, certainty, pausing, forbearance, sincerity, humility, generosity and gratitude.
13 chapters · 29 minSpirituality book summariesIslamic Practice & Guidance book summariesAll authorsAll book summaries