Hawzah News Agency – The merciful prophet of Islam, peace be upon him and his household says:

ما رَأيتُ مَنظَراً إلّا والقَبرُ أفظَعُ مِنهُ.

'I have never seen a scene more horrid than the grave.'

Source: Tanbih al-Khawatir, v. 1, p. 284