Sleep in a state of purity

Sayyiduna Ibn ‘Abbas رضي الله عنهما reported that Nabi صلى الله عليه وسلم said:

‘Purify these bodies and Allah will purify you, for any slave who goes to sleep in a state of purity/wudhu has an Angel that spends the night with him.

Every time he turns over, [the Angel] says, ‘O Allah! Forgive Your slave, for he went to bed in a state of purity.’

(Al-Mu’jamul Awsat of Tabarani, Hadith: 5087)

Allah's Mercy

Quran 3, 190-191

In the creation of the heavens and the earth, and in the alternation of night and day, there are signs for men of understanding. 

Those that remember Allah standing, sitting, and lying down, and meditate upon the creation of the heavens and the earth. "Our Lord! You have not created this in vain. Glory be to You! Protect us from the punishment of fire. [3: 190, 191]