What role did absolute trust in God, or tawakkul, play in classical Sufism?

In classical Sufism, tawakkul, or absolute trust in God, served as a fundamental spiritual practice aimed at deepening one's reliance on the Divine. It was often pursued with such intensity that practitioners considered any concern for the future to be irreligious.1

By fostering this total dependence on God, Sufis sought to purify their inner selves and align their will with the Divine, reflecting the broader Sufi commitment to ikhlāṣ, or absolute purity of intention and action. This practice was deeply rooted in the central Sufi concern of tawḥīd—the realization that there is no deity but God—as mystics strove to recognize God as the sole actor in existence.1