In which article of Constitution of India right to free legal aid is stated?

Article 39A, a Directive Principle inserted by the 42nd Amendment in 1976, directs the State to secure that the legal system promotes justice on a basis of equal opportunity and in particular to "provide free legal aid", so that no citizen is denied justice because of economic or other disabilities. The Supreme Court has also read free legal aid into Article 21 (M.H. Hoskot, 1978; Hussainara Khatoon, 1979), and the Legal Services Authorities Act, 1987 gives effect to it. Article 39 contains other principles of policy, and Article 51A lists fundamental duties.