A verse and its Tafsir
Allah the Exalted says:
"And if you are in a state of ritual impurity, then purify yourselves."
Meaning: If you are afflicted by major ritual impurity (janabah), then perform purification.
The term janabah is so named for this reason:
Because it is a cause for one to avoid the prayer.
Mufradat al-Qur'an by al-Raghib al-Isfahani