Drop upon drop collected will make a river. Rivers upon rivers collected will make a sea.

Sa'adi (1184-1283/1291?) Persian poet [a.k.a. Sa'di, Moslih Eddin Sa'adi, Mushrif-ud-Din Abdullah, Muslih-ud-Din Mushrif ibn Abdullah, Mosleh al-Din Saadi Shirazi, Shaikh Mosslehedin Saadi Shirazi]

The Gulistan, ch. 8, Maxim 42 (1258) [tr. Rehatsek (1964)]