The answer is that he admonishes them with a general exhortation. For example, if it happens that he is speaking in the Friday sermon and admonishes the people, this is good; but it should not be said that he admonished them specifically for the rain-prayer. Rather, it is due to the Friday sermon and the occasion.
“...and that they free themselves from wrongs and abandon mutual rancour...”
His statement, “and that they free themselves from wrongs,” is an instance of mentioning the particular after the general, because freeing oneself from wrongs is part of repentance.
Wrongs is the plural of a wrongful act; it includes wrongs committed against the right of Allah and wrongs committed against the rights of His servants.
An example of a wrong against the right of Allah is failing to pay one’s zakah, or failing to offer an expiation that one owes. He must hasten to discharge this obligation.
An example of a wrong against the rights of people is when one holds something owed to another person, such as money, benefits, or the like. He must likewise free himself of it by fulfilling what is due.
If the right is non-financial, such as backbiting, he frees himself from it by going to the person about whom he spoke and saying, “I spoke about you, so pardon me.” He is not released from its liability except by doing so.
Some scholars have said: If the person about whom he spoke has learned of it, then he should go to him and seek his pardon. But if he has not learned of it, he should not go to him; rather, he should seek forgiveness for him and mention him favourably in the places where he backbit him. For if he were to go to him and ask him to pardon him, pride in sin might overcome him and he might refuse. Some people are unconcerned if their brother comes to them apologizing, and so they refuse to forgive him.
This view is the correct one.
If he says, “I will not pardon you unless you give me ten dirhams...”