No, Albert Einstein did not specifically state that the speed of light (denoted by "c") is constant in all directions and at any point in spacetime. However, this idea is a fundamental principle of Einstein's theory of special relativity.
In Einstein's theory, he proposed two postulates:
The principle of relativity: The laws of physics are the same in all inertial reference frames. In other words, the physical laws governing the universe do not depend on the observer's motion.
The constancy of the speed of light: The speed of light in a vacuum is constant and does not depend on the motion of the source or the observer. This means that the speed of light, denoted by "c," is the same for all observers regardless of their relative motion.
From these postulates, Einstein derived various consequences, such as time dilation, length contraction, and the equivalence of mass and energy (E=mc²). These concepts challenge our intuitive understanding of time and space and have been experimentally confirmed.
So, while Einstein did not explicitly state the phrase you mentioned, the constancy of the speed of light in all directions and at any point in spacetime is a fundamental principle of his theory of special relativity.