Israel's Proclamation of Independence of May 14, 1948, laid down that the elected Constituent Assembly would prepare a constitution for the State of Israel by no later than October 1, 1948. The elections which were held on February 25, 1949, were, in fact, elections to the Constituent Assembly, which held only four meetings. On February 16, 1949, the Assembly adopted the Transition Law, by which it renamed itself the "first Knesset." Because the Constituent Assembly did not prepare a constitution for Israel, the Knesset is the heir of the Assembly for the purpose of fulfilling this function.
Sources: The Knesset