The idea to experiment to understand the world truly took off during the scientific revolution in the 17th century. But various earlier thinkers refer to its importance. Among them Aristotle, Jabir ibn Hayyan and Hasan ibn Al-Haytham. Here the full quote from Jabir:
‘The first essential in chemistry is that thou shouldest perform practical work and conduct experiments, for he who performs not practical work nor makes experiments will never attain to the least degree of mastery.’
"The Great World History Book"