In what part of Hamlet can i find the soliloquy where Hamlet says "Frailty thy name is woman"?

That would be in the first act, after the death of his father when he sits brooding in his room and his mother and uncle, to whom she had become enamored, enter to find why he stays in his darkened room. When he sees his mother recently having lost her husband flirting with his uncle he remarks, "Frailty, thy name is woman," believing she should grieve longer.