Sleeping with firm belief surpasses doubtful prayer
Nahj al-Balāgha|Volume 1|Book 3|Chapter 97
٩٨. سَمِعَ (عليه السلام) رَجُلًا مِنَ الْحَرُورِيَّةِ يَتَهَجَّدُ وَيَقْرَأُ فَقَالَ: نَوْمٌ عَلَى يَقِينٍ خَيْرٌ مِنْ صَلَاةٍ فِى شَكٍّ.
97. Amīr al-mu’minīn, peace be upon him, heard about a Kharijite who said the mid-night prayers and recited the Qur’ān, then he said: Sleeping in a state of firm belief is better than praying in a state of doubtfulness.