Tafsir of An-Najm 53:46

(From a drop when it is emitted)

That is, when it flows into the womb. It is said: amna al-rajulu (the man emitted) and mana (he emitted), meaning the same thing. Al-Akhfash said: it means when it is ordained (or measured out). It is said: mana laka al-mani, meaning the ordainer has ordained for you, and from this is the mann (a unit of weight) by which things are weighed, according to what has been said, and the maniyyah (death), which is the ordained lifespan of a living being.