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 is His slave and Messenger.
Imaam Ibn al-Qayyim clarified the meaning of this authentic hadeeth and other ahaadeeth with the same meaning in regard to informing about the Muslim being protected and not being harmed if he says some specific mention of Allaah and some chapters or verses for seeking refuge in Allaah from harm; so Ibn al-Qayyim said in Zaad al-Ma’aad:
“You should know that natural divine medicines are beneficial after the disease happens, and they prevent the disease from taking place as well, but if the disease happens, it does not harm even if it is painful, and the natural medicines are beneficial after the disease happens. The chapters or verses for seeking refuge in Allaah and the mention of Allaah either prevent the occurring of these reasons, or they prevent their effect according to the perfectness of seeking refuge, its strength and weakness. Ruqyah (healing through the Quran and supplications) and seeking refuge are used to protect one’s health and to remove disease. The first: as in the hadeeth reported by Al-Bukhari and Muslim that ‘Aa’ishah said, 'When the Prophet goes to his bed, he used to blow in his hands and recite chapters 112, 113 and 114, then he wipes over his face and over whatever he could reach of his body with his hands.' There is also the Marfoo' hadeeth (which is attributed to the Prophet ) by Abu ad-Dardaa’ that reads, 'O Allaah, You are my Lord, there is no god besides You, I rely upon You and You are the Lord of the Mighty Throne.' We have mentioned it before and it includes the following: 'Whoever says it at the beginning of his day, no calamity will befall him until the evening, and whoever says it at the end of his day, no calamity will befall him until the morning.' Also, the hadeeth by Al-Bukhari and Muslim that reads, 'Whoever recites the two last verses from Soorah Baqarah [Quran 2: 285-286]; they will be sufficient for him.' Also, the hadeeth in Saheeh Muslim reads, 'Whoever descends at any place and says, 'I seek refuge in the perfect words of Allaah from the evil that He has created,' then nothing will harm him until he leaves that place.' Also, Abu Daawood reported in his Sunan that the Prophet when he was travelling, used to say by night, 'O earth, my Lord and your Lord is Allaah; I seek refuge in Allaah from your evil, the evil of what you contain, the evil of what has been created in you, and the evil of what creeps upon you; I seek refuge in Allaah from lions, from large black snakes, from other snakes, from scorpions, from the evil of the jinn that inhabit a settlement, and from a parent and his offspring.' As regards the second one: it is as we have already mentioned: Performing Ruqyah with Al-Faatihah [the Opening Chapter of the Quran], and performing Ruqyah when being stung by a scorpion or anything else as will be discussed hereunder." [End of quote]
So, it becomes evident that the mention of Allaah and the chapters or verses for seeking refuge in Allaah from harm prevent the occurrence of harm, but some harm might take place because the one who seeks refuge does not have full relying on Allaah when seeking refuge in Him, and this is similar to supplicating at times of calamity, the calamity might not happen and sometimes it happens; this is depending on the strength of the one who supplicates. Ibn al-Qayyim said:
“Supplications and prayers for seeking refuge in Allaah are like weapons, and a weapon is only as effective as the one using it, not just based on how sharp it is. So, if the weapon is perfect and flawless and the arm that is using it is strong and there is nothing to nullify its effectiveness, it will cause damage to the enemy. And whenever one of these three elements is absent, the effect will be held back. So if the supplication itself is not good, or the one supplicating does not have both his heart and tongue present when making it, or there is some element present to prevent it from being answered, then it will have no effect.” [End of quote]
Allaah knows best.