The believer accepts realities beyond the reach of the senses — on the authority of revelation, not guesswork.
Al-ghayb (الغيب) is everything hidden from us that we cannot perceive with our senses, and which is known only through Allah and His Messenger ﷺ. The Quran opens by describing the God-fearing as precisely those who believe in it — not blindly, but on the firm testimony of revelation.
الَّذِينَ يُؤْمِنُونَ بِالْغَيْبِ وَيُقِيمُونَ الصَّلَاةَ وَمِمَّا رَزَقْنَاهُمْ يُنفِقُونَ
"Who believe in the unseen, establish prayer, and spend out of what We have provided for them."
Al-Baqarah 2:3
No creature — not an angel, prophet, jinn, or saint — possesses independent knowledge of the unseen. Allah may disclose some of it to a messenger by revelation (Al-Jinn 72:26–27), but its keys remain His alone.
وَعِندَهُ مَفَاتِحُ الْغَيْبِ لَا يَعْلَمُهَا إِلَّا هُوَ ۚ وَيَعْلَمُ مَا فِي الْبَرِّ وَالْبَحْرِ
"And with Him are the keys of the unseen; none knows them except Him. And He knows what is on the land and in the sea…"
Al-An'am 6:59
The Quran specifies five matters of the unseen that Allah keeps to Himself — sometimes called the "five keys": "Indeed, Allah [alone] has knowledge of the Hour and sends down rain and knows what is in the wombs. And no soul knows what it will earn tomorrow, and no soul knows in what land it will die." (Luqman 31:34)
Because the unseen belongs to Allah alone, claiming to know it through fortune-telling (kahanah), astrology (tanjeem used to predict events), or "reading" the future is a serious sin and a door to shirk. The Prophet ﷺ said: "Whoever goes to a fortune-teller (ʿarrāf) and asks him about something, his prayer will not be accepted for forty nights." (Muslim). And: "Whoever goes to a fortune-teller and believes what he says has disbelieved in what was revealed to Muhammad ﷺ." (Reported by Abu Dawud and others).
Using the stars merely for guidance in direction or seasons is permitted; using them to claim knowledge of destiny and the future is forbidden, for that is reaching for the keys that belong to Allah alone.