Surah Al-Muzzammil — Ayah 5 (73:5)

English translation (Saheeh International)

Indeed, We will cast upon you a heavy word.¹

1. - i.e., the revelation, which when descending on the Prophet (ﷺ) bore down upon him with a great weight. Another meaning is "important ordinances."

Brief commentary

I am going to send down on you, O Messenger, the Qur’ān, which is a heavy word, due to the obligations, limits, provisions, etiquettes etc. that it contains.