I would like to know how Muslims can differentiate between calamities that are caused by an evil eye, and others that are not related to that. Can we cure the person who has been harmed by an evil eye without knowing who gave him the evil eye?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

In order to differentiate between calamities that result from an evil eye and others, we should know the symptoms of the effect of an evil eye. Usually, an evil eye causes symptoms that can not be treated by doctors, such as joints diseases, laziness, insomnia, ulcers that appear on the skin and aversion to home, school, family and society. In addition, there may be some psychological and neurological diseases. Envied people are usually pale, angry, having ailments, prone to depression, sighing and forgetfulness and feel heavy headed and feel that their shoulders are heavy. They also feel that their limbs are stinging, their bodies are hot and their limbs are cold.

‘Abd Al-Khaaliq Al-‘Attaar said that an evil eye could affect a person’s wealth, body, and children, according to the object to which the evil eye is directed. If the person himself got the evil eye, he would be afflicted with psychological symptoms such as detesting school, college, work and study and would become less intelligent. Moreover, he may become introverted and prefer to live away from his family. He may also feel that even his most beloved people do not love him.

To conclude, envy can be determined by observing its symptoms and the person can be treated with Islamic Ruqyah (healing with the Quran). This would include reciting Soorat Al-Faatihah, the verse of Al-Kursi, the last verses of Soorat Al-Baqarah starting from what Allaah The Almighty Says (which means): {The Messenger has believed in what was revealed to him from his Lord, and [so have] the believers.}[Quran 2:285] up to the end of the Soorah. Also, reciting what Allaah The Almighty Says (which means): {And indeed, those who disbelieve would almost make you slip with their eyes when they hear the message, and they say, "Indeed, he is mad."}[Quran 68:51], Soorat Al-Ikhlaas, Al-Falaq, An-Naas, and reciting some invocations said by the Prophet, sallallaahu ‘alayhi wa sallam. It was narrated on the authority of Ibn ‘Abbaas both, that the Prophet, sallallaahu ‘alayhi wa sallam, used to say: “U‘eethuka bikalimaatillaahi at-taammah min kulli shaytaanin wa haammah wa min kulli ‘aynin laammah (I seek refuge with the perfect words of Allaah from every devil or harmful insect and from any envying eye).” [Al-Bukhari]

It was narrated on the authority of Abu Sa‘eed Al-Khudri that the Prophet, sallaallaahu ‘alayhi wa sallam, used to say: “Bismillaahi arqeek min kulli shay’in yu’theek, min sharri kulli nafsin wa ‘ayni haasid. Allaahu yashfeek, bismillaahi arqeek (I make Ruqyah for you with the name of Allaah from anything that would harm you and from any eye that would envy you. May Allaah cure you. I make Ruqyah for you in the name of Allaah.)” These words should be read directly on the patient then read into water which he should drink and then use to perform Ghusl (ritual bath). This applies if the person who gave the evil eye is unknown.

However, if the person who envied him is known, he should be ordered to perform Ghusl or ablution, then the diseased person should perform Ghusl using this same water. It was narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said that an evil eye and its effect existed, then he ordered the one who envied someone to take a shower if he was asked to do so. [Muslim]

It was narrated on the authority of ‘Aa’ishah that the Prophet, sallallaahu ‘alayhi wa sallam, used to order the one who gave an evil eye to perform ablution, then the afflicted person  would use that water to perform Ghusl. [Abu Daawood]

And Allaah Knows best.