Tafsir of Ya seen 36:28

And We sent not against his people after him an army from the heaven, nor was it needful for Us to send. Allah tells us that He took revenge on his people after they had killed him because He, may He be blessed and exalted, was angry with them, for they had disbelieved in His Messengers and killed His close friend. Allah tells us that He did not send an army of angels, nor did He need to send them, to destroy these people; the matter was simpler than that. This was the view of Ibn Mas`ud. According to the reports of Ibn Ishaq from some of his companions concerning the Ayah,

وما أنزلنا على قومه من بعده من جند من السماء وما كنا منزلين

(And We sent not against his people after him an army from the heaven, nor was it needful for Us to send). He said: "`We did not seek to outnumber them, for the matter was simpler than that.''

إن كانت إﻻ صيحة واحدة فٳذا هم خامدون