Reference: Siyar A’laam an-Nubalaa – Volume 4, Page 321
Sa’eed ibn Jubayr said:
at-Tawakkul (complete and total trust) in Allaah [alone] is intertwined with eemaan.
And he would supplicate [to Allaah, saying]:
الَّلهُمَّ إِنِّي أَسْأَلُكَ صِدْقَ التَّوَكُّلِ عَلَيْكَ وَ حُسْنَ الظَّنِّ بِكَ
O Allaah, indeed I ask of You [to bless me] with sincere and genuine trust in You, and to [always] have good suspicion of You.