Short answer
No. Killing a spider is not haram, especially one that is harmful or in your home. There is no authentic hadith that forbids it or that makes it a sunnah. The kinder choice for a harmless spider is to put it outside, and you should never kill any creature with fire or in a way that makes it suffer.
Killing harmful insects and creatures is mubah (permitted). Killing a harmless creature for no reason is disliked, and killing any creature by burning or torture is makruh tahrimi.
The four schools agree on this.
Explanation
Spiders are mentioned in the Quran in a surah named after them, al-Ankabut. Allah compares those who rely on other than Him to a spider that builds a home, and the weakest of homes is the home of the spider. This is a parable. It does not make spiders sacred, and it does not command killing them.
Many Muslims have heard that the spider protected the Prophet ﷺ by spinning a web over the cave of Thawr during the Hijrah, so it must not be killed. That story appears in some books of hadith and sirah, and scholars have discussed the strength of its chain. Even if it is accepted, it does not turn into a ruling that spiders may never be killed. The other popular saying, that leaving spider webs in the house brings poverty, has no authentic source either.
The rule that does apply is the general one for all creatures:
- A spider that may bite or harm you, such as a venomous one, can be killed.
- A harmless spider in the house can be removed; catching it in a cup and putting it outside is kind and rewarded.
- Do not kill any creature for fun, and do not burn it. A prophet who burned a whole colony of ants was rebuked by Allah, and the Prophet ﷺ said only the Lord of the fire may punish with fire.
- Clearing webs is part of keeping a clean home, and that is fine.
If you need pest control for a real infestation, use the quickest method available. The four schools agree on these principles. For ants, which have a specific hadith, see is it haram to kill ants.
The evidence
Quran, Surah Al-Ankaboot 29:41
مَثَلُ ٱلَّذِينَ ٱتَّخَذُوا۟ مِن دُونِ ٱللَّهِ أَوْلِيَآءَ كَمَثَلِ ٱلْعَنكَبُوتِ ٱتَّخَذَتْ بَيْتًۭا ۖ وَإِنَّ أَوْهَنَ ٱلْبُيُوتِ لَبَيْتُ ٱلْعَنكَبُوتِ ۖ لَوْ كَانُوا۟ يَعْلَمُونَ ﴿٤١﴾
The example of those who take allies other than Allah is like that of the spider who takes a home. And indeed, the weakest of homes is the home of the spider, if they only knew.
Spiders appear in the Quran as a parable, not as a sacred animal.
Sahih al-Bukhari 3019
Sahih... قرصت نملة نبيا من الأنبياء فأمر بقرية النمل فأحرقت ...
"An ant bit one of the prophets, so he ordered the ant colony to be burned, and Allah rebuked him for it."
Killing creatures in excess, and burning them, is blamed.
Sunan Abi Dawud 2675
Grading to be checked... إنه لا ينبغي أن يعذب بالنار إلا رب النار ...
"No one should punish with fire except the Lord of the fire."
Killing insects with fire is not allowed.
Where the ruling is recorded
- al-Fatawa al-Hindiyya, Kitab al-Karahiyya, chapter on killing animals. Harmful creatures may be killed; harmless ones should not be killed without reason, and burning is disliked.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.