In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Allaah [The Most High] said:
اللَّهُ لَا إِلَٰهَ إِلَّا هُوَ ۚ وَعَلَى اللَّهِ فَلْيَتَوَكَّلِ الْمُؤْمِنُونَ
The strength of one’s Tawakkul [i.e. reliance upon Allaah] or its weakness depends on the strength or weakness of [his or her] Eemaan. Whenever the Eemaan of person is strengthened, Tawakkul is stronger. And when Eemaan is weak, Tawakkul becomes weak. And when Tawakkul becomes weak, it is proof that Eemaan is weak and that has to be the case. Allaah [The Most High] tied Tawakkul to Ibaadah, Eemaan, Islaam, Taqwaa and Guidance. [Source: An Excerpt from ‘Badaa’i At-Tafseer Limaa Fassarahu Al-Imaam Ibnul Qayyim’ Vol 3, page 159. Slightly paraphrased]