In the Holy Qur'an

Successful indeed are the believers who are humble in their prayers (23:1-2)

In the Traditions

O God,

bless Muhammad and His Household,
delight my soul through Thy decree,
expand my breast through the instances of Thy decision,
give to me a trust through which i may admint
that Thy decree runs only to the best,

and let my gratitude to Thee
for what Thou hast taken away from me
be more abundant than my gratitude to Thee
for what Thou hast conferred upon me!

Preserve me from imagining any meanness
in someone who is destitute
or imagining any superiority
in someone who posseses wealth,

for the noble is he
whom obedience to Thee has ennobled
and the exalted is he
whom worship of Thee has exalted!

Excerpt of Supplication In Satisfaction with the Decree
by Imam Zainul Abideen