Fathwa - The Ruling Concerning Putting a Knife on a Child in Order to Protect Him.

Question:
I have seen some people placing a knife on their small children
saying, "This is so the Jinn do not come to him." Is this practice
correct?
Answer:
This is an objectionable act and there is no soundsource for it. It is
not allowed to do such a thing. What is legally sanctioned is to seek
refuge from them by Allah's complete words from every devil and
poisonous pest, as has been confirmed from the Prophet (sallallaahu
'alaihi-wasallam). He useto seek protection by those words for his
grandsons al-Hasan and al-Husain ibn Ali. It is also sanctioned to
makeduafor them by asking Allah to protect them from every evil.
As for putting a knife or something similar, or iron, wood or other
substances, with the belief that such will protect them from the jinn,
it is an evil practice that is not allowed.
Similar is the ruling withrespect to hanging an amulet over them,
whichis what is called al-tama'im. This is not allowed because the
Prophet (sallallaahu 'alaihi-wasallam) said,
" Whoever hangs an amulet, Allah will not complete [his affair] for him. "[1]
In another narration the Prophet (sallallaahu 'alaihi-wasallam) said,
" Whoever wears an amulet has committedShirk."[2]
May Allah bestow understanding of the religion upon all Muslims, and
steadfastness in the religion. We seek refuge for ourselves and them
from everything that differs from His pure law.