Is prayer performed with Tayammum valid if the worshipper forgot the presence of usable water?

Primary text

The prayer performed with Tayammum (dry ablution) when the worshipper forgot water he possessed, even if it was in his baggage or a reachable place, is invalid according to the view adopted by Ahmad ibn Hanbal and Al-Shafi'i. The evidence for this stance is rooted in the principle that purification rituals which are obligatory upon conscious remembrance do not become waived merely through forgetfulness, analogous to a person praying while forgetting they were in a state of major impurity (hadath) who later remembers, or a person whose established period of wiping over socks (mas'h) expires before prayer but who proceeds anyway. This situation is distinguished from cases where one is genuinely unable to find water, as here, the individual is considered negligent (*mufrit*) for failing to seek out the available water.