The first written record of this common English proverb is a sonnet written in 1570 by Thomas Howell:
Count not thy Chickens that unhatched be,
Weigh words as wind, till thou find certainty
Many languages have proverbs that convey a similar principle.
Swahili:
Tujivune hatimaye.
French:
Il ne faut pas vendre la peau de l’ours avant de l’avoir tué.
Arabic:
لا تشتري السمك وهو في البحر بل انتظر حتى يصطاد
German:
Man soll den Tag nicht vor dem Abend loben.
Latin:
Ante victoriam ne canas triumphum
Portuguese:
Não conte com o ovo dentro da galinha.