Tafsir of Qaf 50:37

إن في ذلك لذكرى

Verily, therein is indeed a reminder, (and a lesson),

لمن كان له قلب

for him who has a heart, meaning, a sound understanding with which he comprehends, or, a good mind, according to Mujahid,

أو ألقى السمع وهو شهيد

or gives ear while he is heedful. meaning, he hears the speech, comprehends and understands it in his mind and grasps its indications with his intellect. Mujahid said that,

أو ألقى السمع

(or gives ear), means, he does not talk to himself but listens with an attentive heart. Ad-Dahhak commented, "The Arabs would say that someone has given ear when he hears with his ears, while his heart is present and not absent.'' Ath-Thawri and several others said similarly. The statement of Allah the Exalted and Most Honored;

ولقد خلقنا السماوات واﻻرض وما بينهما في ستة أيام وما مسنا من لغوب