They enjoyed Salih preached to them, warning them that the punishment of Allah could overtake them and reminding them of the blessings that Allah had bestowed upon them, by giving them ample provision and making them safe from all kinds of dangers, giving them gardens and flowing springs, and bringing forth for them crops and fruits.
(and date palms with soft clusters.) Al-`Awfi narrated from Ibn `Abbas, "Ripe and rich." `Ali bin Abi Talhah narrated from Ibn `Abbas that this meant growing luxuriantly. Isma`il bin Abi Khalid narrated from `Amr bin Abi `Amr -- who met the Companions -- from Ibn `Abbas that this means, "When it becomes ripe and soft." This was narrated by Ibn Abi Hatim, then he said: "And something similar was narrated from Abu Salih."
(And you hew out in the mountains, houses with great skill.) Ibn `Abbas and others said, "With great skill." According to another report from him: "They were greedy and extravagant." This was the view of Mujahid and another group. There is no contradiction between the two views, because they built the houses which they carved in the mountains as a form of extravagant play, with no need for them as dwelling places. They were highly skilled in the arts of masonry and stone-carving, as is well known to anyone who has seen their structures. So, Salih said to them:
(So, have Taqwa of Allah, and obey me.) Pay attention to that which could benefit you in this world and the Hereafter; worshipping your Lord Who created you, who granted you provisions so that you could worship Him alone and glorify Him morning and evening.
(And follow not the command of the extravagant, who make mischief in the land, and reform not.) meaning, their chiefs and leaders, who called them to Shirk, disbelief and opposition to the truth.