Salamo3alaykom, I've a question regarding ZamZam water. I've read a hadeeth stating that ZamZam water is for whatever is drunk for, but this to which extent and how much of it should I drink? For example me I've always been stubborn and often I find it quite difficult to understand some concepts, can ZamZam water improve a person at a neurological level or make the person very intelligent if the person wishes so?
The hadith you refer to is qualified as weak (see for example here the doubt expressed by al-Hakim from Nishapur about one narrator who basically is truthful) or fabricated by some scholars others consider it sahih, but maybe the most correct view is that it reaches the level of hassan (due to the sum of narrations and reports containing similar information) and is for example mentioned in Sunan ibn Majah:
“I heard the Messenger of Allah (ﷺ) say: ‘The water of Zamzam is for whatever it is drunk for.’”
Most of the narrations
And the prophet() also described it as:
It is blessed (water) and it also serves as food. (in this long hadith in Sahih Muslim)
As for the benefits or the interpretation of the (first) hadith we can only rely on what we know or hear:
- Among the first who considered this hadith as sahih was the scholar Sufyan ibn 'Uyaynah: Who when asked whether he would qualify this hadith as true answered: Yes. The asker than said I've recently drunk it with the intention to hear hundered hadith from you. And ibn 'Uyaynah did so (Source this fatwa -in Arabic- on islamway). This story was narrated by ad-Dynawri الدينوري in his al-Mujalasah المجالسة وجواهر العلم (see also fatwa islamqa #1698).
In the fatwa above you may also read:
Al-‘Allaamah al-Abbi (may Allaah have mercy on him) said:
“(The water) is for whatever purpose it is drunk for, and Allaahmade it food and drink for Ismaa’eel and his mother Haajar.”
Ibn al-Mubaarak entered Zamzam and said, “O Allaah, Ibnal-Mu’ammal told me, from Abu’l-Zubayr from Jaabir that the Messenger of Allaah(peace and blessings of Allaah be upon him) said: ‘The water of Zamzam is forwhatever purpose it is drunk for,’ so, O Allaah, I am drinking it (to quench) mythirst on the Day of Resurrection.”
Imam as-Suyuti has been said to have drunk from it with the intention to reach a level of fiqh like that of Siraj ad-Dyn al-Balqini سراج الدين البلقيني (who was a teacher of ibn Hajar and the father of as-Suyuti's teacher 'Alamu a-d-Dyn) and in hadith-sciences of ibn Hajar al-'Asqalani (Source Arabic Wikipedia).
More references (in Arabic):