Leviticus 15:8

וכי ירק הזב בטהור AND IF HE THAT HATH THE ISSUE SPIT UPON ONE WHO IS CLEAN — and he (the clean person) comes in contact with it (the spittle; i. e. it actually falls upon him) or even if he only bears it (i. e. it has, for instance, fallen upon a stick which he is carrying) then HE SHALL BE UNCLEAN UNTIL THE EVEN, for the spittle communicates uncleanness through carrying it (cf. Niddah 55b).

וְכִֽי־יָרֹ֥ק הַזָּ֖ב בַּטָּה֑וֹר וְכִבֶּ֧ס בְּגָדָ֛יו וְרָחַ֥ץ בַּמַּ֖יִם וְטָמֵ֥א עַד־הָעָֽרֶב׃

And if he that has the issue spit upon him that is clean; then he shall wash his clothes, and bathe himself in water, and be unclean until evening.