There is a difference of opinion if ‘mursalaat’ refers to angels or winds, but in a literary context, ‘winds’ is a more appropriate definition.
Allah azza wa jal says:
وَالْمُرْسَلَاتِ عُرْفًا and by the winds that scatter [77:1]: ‘urf literally means the mane of a horse. If a horse has no reins, the rider only has the mane to hold on too, and if the rider let’s go, the horse will go wild.
This first ayah is showing how if Allah ta’ala let a wind go, it would spread wildly without control.
فَالْعَاصِفَاتِ عَصْفًا and by the winds that blow violently [77:2]: the “fa” at the beginning of this verse shows reason, due too, because of the mursalaati ‘urfaa: al-’aasifaati ‘asfa. ‘asf literally means inconsiderate movement, such as a bulldozer. (Think of a car coming straight at you on the highway, if that car doesn’t move, and rams right into you–that is ‘asf) It is a merciless wind that destroys everything in its path.
In these two verses, Allah ta’laa is talking about winds that brings destruction. Why? This is a makkee surah, and Allah ta’ala is reminding the Quraysh–those who mock at the Prophet sal Allahu alayhi wa sallam to bring the punishment–these winds of punishment CAN be let go and it has been done before, no intricate planning or arrangement is required for your destruction.
In Suratul Haqqah [69:6], Allah ta’ala describes the scene of ‘Aad who were destroyed by a wind: for eight days their whole city were being tossed around like it was nothing.
Then Allah ta’ala says in the next ayah:
وَالنَّاشِرَاتِ نَشْرًا and by the winds that scatter [77:3]: this ayah begins with a ‘wa’ so we know it is a new oath. Allah ta’ala swears by the winds that do nashr. Nashr means to spread randomly all over, such as the act of taking seeds and scattering them on the soil.
An-naashiraat are those winds that distribute. What do they distribute? Clouds that bring the rain. If these winds did not distribute the clouds, then cities would suffer from drought. Modern science learns now that pollen is also distributed by winds, so without these winds there would be no vegetation. These naashiraat distribute from both the sky (rain) and the ground (vegetation).
This verse shows the life that the winds carry, while the first two verses displayed death and destruction.
Allah azza wa jal continues:
فَالْفَارِقَاتِ فَرْقًا and by those winds that separate: farq means to distribute and separate, with a very precise division.
These winds distribute mercy, just as the first two winds sent punishment. This verse shows us that all of these winds, either bringing mercy or punishment, are precisely distributed.
فَالْمُلْقِيَاتِ ذِكْرًا and by those that deliver a message: Both of these winds, the ones of mercy and the ones of destruction, carry a reminder for the people. The winds of mercy remind us that these winds bring rain, which is a rizq (provision) from the sky, showing we are totally dependent on Allah ta’ala, such as a man who is feeding a caged animal–the animal is totally dependent on the master. These verses remind us no matter how disobedient or how wild we are: we depend totally on Allah. When the rain falls from the sky that these winds have scattered, we see the dead earth being brought to life, reminding us that we will be resurrected just as the dead land.
These reminders are:
عُذْرًا أَوْ نُذْرًا as a justification or to warn: ‘udhra means to receive an excuse or a lesson, or an ignoring. There are two people mentioned in this verse: those who take a reminder of these winds, and those who ignore the reminder.
But either way:
إِنَّمَا تُوعَدُونَ لَوَاقِعٌ Surely, what you have been promised will definitely come to pass: the promise of the Day of Judgment, of Resurrection and the destruction of those who disobey Allah. Those who enjoy the mercy of these winds, the rain, the vegetation, the rizq, they will be destroyed.
May Allah ta’ala make us among those who benefit from the reminder,