According to Sass (5), already in the Middle Kingdom there were some cases of matres lectionis, i.e. consonant graphemes which were used to transcribe vowels in foreign words, namely in Punic (Jensen 290, Naveh 62), Aramaic and Hebrew (he, waw, jod; sometimes even aleph; Naveh 62). Naveh (ibid.) notes that the earliest
Aramaic and
Hebrew documents already used matres lectionis. Some scholars argue that therefore the Greeks must have borrowed their alphabet from the Arameans. But the practice has older roots: the Semitic cuneiform alphabet of Ugarit (13th ct. BC) already has matres lectionis (Naveh 138).
Bibliography:
Jensen, Hans. 1970. Sign Symbol and Script. London: George Allen and Unwin Ltd. Transl. of Die Schrift in Vergangenheit und Gegenwart. VEB Deutscher Verlag der Wissenschaften. 1958, as revised by the author.
Naveh, Joseph. 1979. Die Entstehung des Alphabets. Transl. of Origins of the Alphabet. Zürich und Köln. Benziger.
Sass, Benjamin. 1991. Studia Alphabetica. On the origin and early history of the Northwest Semitic, South Semitic and Greek alphabets. CH-Freiburg: Universitätsverlag Freiburg Schweiz. Göttingen: Vandenhoeck & Ruprecht.