يَتَفَطَّرْنَ (burst apart). It has been stated in the above hadith that the load of angels began producing such crackling sounds in the heavens as are produced when excessive load is placed on something. This tells us that angels have weight and this is not beyond reason, because it is confirmed that angels also have physical bodies, even though very light in weight. And even light bodies add up to a considerable load when they are in huge numbers. (Bayan-u1-Qur'an)
These angels in the heavens proclaim the perfection of their Lord and utter His praises. They also ask for forgiveness of the dwellers of this earth who do not give what is due to Allah's greatness, rather indulge in associating others with Him and in infidelity and hence become liable to suffer scourge. Their asking for forgiveness for disbelievers is for a limited period only and is a supplication that some severe worldly scourge may not befall the humans which may destroy all of them; their safety against ordinary punishments of this world and the real scourge of the Hereafter are not included in this supplication. And Allah, the Almighty accepts this supplication, and saves them from the general scourge in this world. It must be understood thoroughly that Allah and Allah alone is the forgiver and Merciful although this forgiveness of infidels is for a limited duration and is limited to this world only.