Shaykh Ibn Uthaymeen رحمه الله:

"Even the phases of the moon remind us of life and death.

Born weak, it gains strength to its full potential, then weakens and disappears."

[Explanation of al-Usool ath-Thalaathah (p. 48)]

Sheikh Muhammad ibn Saalih al-'Uthaymeen mentioned the following in his explanation of Kitab al-Tawheed:

[من طهر قلبه من المعاصي كان أفهم للقرآن ومن تنجس قلبه بالمعاصي كان أبعد فهما عن القرآن.]

"Whoever purifies his heart from sins will have more understanding of the Qur'an, but whoever sullies his heart with sins will be further from understanding the Qur'an."

[al-Qawl al-Mufeed 'alaa Kitab al-Tawheed 2/37]

ʿAmr reported:

"Al-Ḥasan used to say: 'Son of Ādam, beware of procrastination.

You are involved in today and not tomorrow.

If you reach tomorrow, then be wise tomorrow as you are today and if you have no tomorrow, then you will not regret what you missed today.”'

Source | Ibn Abī ʾl-Dunyā, Qaṣr al-Amal Vol 1 Pg 144

الله المستعان

'Abdullah bin Tha'labah said:

"Do you laugh, when your shrouds might already have been sewn by the tailor?"

Source | Al'-Āqibah Pg 88

'Abdullah Ibn Mas'ūd رضي الله عنه‎ said:

“For me to bite onto hot coal until it cools down is more beloved to me than to say about something Allāh has decreed:

'I wish it did not occur'”

Source | Az-Zuhd Li Abī Dāwūd: 136

Shaykh Muḥammad Ṣāliḥ Ibn 'Uthaymeen رحمه الله said: "Righteous actions, including fasting in the (first) ten days of Dhul Hijjah are move beloved to Allāh سبحانه و تعالى than righteous actions of the last ten days of Ramadān, yet the people are heedless…