Allah informs that Thamud rejected their Messenger because of the injustice and transgression they practiced. This was said by Mujahid, Qatadah and others. Therefore, this resulted in a rejection in their hearts for the guidance and conviction their Messenger came to them with.

[إِذِ انبَعَثَ أَشْقَـهَا ]

(When their most wicked went forth.) meaning, the most wicked person of the tribe, and he was Qudar bin Salif, the one who killed the she-camel. He was leader of the tribe of Thamud, and he is the one whom Allah refers to in His saying,

[فَنَادَوْاْ صَـحِبَهُمْ فَتَعَاطَى فَعَقَرَ ]

(But they called their comrade and he took (a sword) and killed (her).) (54:29) This man was mighty and respected among his people. He was of noble lineage and a leader who was obeyed. This is just as Imam Ahmad recorded from `Abdullah bin Zam`ah. He said that the Messenger of Allah gave a sermon in which he mentioned the she-camel and he mentioned the man who killed her. Then he said,

«[إِذِ انبَعَثَ أَشْقَـهَا ]

انْبَعَثَ لَهَا رَجُلٌ عَارِمٌ عَزِيزٌ مَنِيعٌ فَي رَهْطِهِ مِثْلُ أَبِي زَمْعَة»

((When their most wicked went forth.)( A strong and mighty man who was invincible among his tribe, like Abu Zam`ah, went forth to her.) This Hadith was recorded by Al-Bukhari in his Book of Tafsir, and Muslim in his Book of the Description of the Hellfire. At-Tirmidhi and An-Nasa'i both recorded it in their Sunans in their Books of Tafsir.