What level of fear justifies the allowance of Tayammum (dry ablution) for the sick or fearful person?
Chapter on Tayammum
Al-Mughni
Book of Purification
Primary text
The allowance for Tayammum is established if a person fears an increase in illness, a delay in recovery, an indecent matter, or an unbearable pain. This view is held by the prevailing position in the Hanafi school, the second opinion of Al-Shafi'i, and is considered correct. The evidence for this is the general statement in the Quran: "and if you are sick or on a journey" (Quran 4:43). Furthermore, allowance is granted if one fears the loss of property, personal harm from a thief or a wild beast, or if water is only available at an excessive price. The allowance for Tayammum in these circumstances is prioritized because neglecting standing in prayer or delaying fasting is not limited only to the fear of death.
Supporting text
It is narrated from Ahmad, and it is one opinion of Al-Shafi'i, that only the fear of total physical destruction (Talf) permits Tayammum. Furthermore, a sick or wounded person who does not fear harm from using water, such as someone suffering only from a headache or mild fever, or someone who has access to hot water without detriment, is obligated to use the water, as the allowance for Tayammum is established to negate harm, which is absent in their case.