All praise is due to Allah, and may peace and blessings be upon the Messenger of Allah. To proceed:
The basic principle is that a Muslim should guard his tongue and speak only what is good. The Prophet ﷺ said:
“Whoever believes in Allah and the Last Day should speak good or remain silent.”
Therefore, a person should pause before speaking. If what he intends to say is certainly good, he may speak; otherwise, remaining silent is safer, even if the speech is permissible, for fear that it may lead to something forbidden or disliked.
The Prophet ﷺ warned against letting the tongue speak without restraint. After taking hold of his tongue, he said to Mu‘adh, may Allah be pleased with him:
“Restrain this.”
He also explained that many of the causes that lead people into Hell are the consequences of what their tongues utter.
Among the matters that have been prohibited from being discussed are the following:
1. Speaking ill of the Companions of the Prophet ﷺ
The Prophet ﷺ said:
“When my Companions are mentioned, then refrain from speaking.”
We must therefore guard our tongues against insulting the Companions or criticizing them unjustly, and refrain from delving into the disagreements that occurred among them, while believing in their virtue and that Allah is pleased with them. Allah praised them in the Qur’an and instructed those who came after them to say:
“Our Lord, forgive us and our brothers who preceded us in faith, and place no resentment in our hearts toward those who believe.”
2. Speaking about the stars through astrology and claiming knowledge of the unseen
The prohibition concerns astrology that treats the movements and positions of stars as indicators of earthly events and future occurrences. This includes claiming to know happiness or misery, marriage, travel, provision, or calamities through the stars.
However, using the stars to determine directions, times, and similar permissible matters is not what this prohibition refers to.
3. Delving deeply into divine predestination without knowledge
Divine predestination is among the secrets of Allah, Exalted be He, whose true reality He has not revealed to creation. A Muslim should therefore not attempt to delve into its details through personal reasoning and philosophy, nor object to Allah’s actions and judgments. Rather, one should believe that everything occurs by Allah’s decree and predestination, that whatever has befallen a person could never have missed him, and that whatever has missed him could never have befallen him.
This does not mean abandoning the study of Islamic creed or the understanding of predestination through authentic evidence. Rather, what is prohibited is going to excessive lengths, engaging in needless speculation, and arguing about matters whose true reality cannot be comprehended.
A Muslim must therefore guard his tongue, speak about what benefits him, and refrain from what harms him in his religion and worldly life, especially when it comes to insulting the Companions, astrology and claims to knowledge of the unseen, and philosophical speculation about the mysteries of divine predestination.
And Allah knows best.