Whoseover interrupts the conversation of others to make a display of his own wisdom, certainly betrays his ignorance.
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]
Gulistān [Rose Garden, گُلِستان], ch. 8 “Rules for Conduct in Life,” Maxim 82 (1258) [tr. Gladwin (1806)]
(Source)
Alternate translations:Whoever interrupts the conversation of others to display the extent of his wisdom, will assuredly discover the depth of his folly.
[tr. Eastwick (1852), #82]Who interrupts the conversation of others that they may know his excellence, they will become acquainted only with the degree of his folly.
[tr. Burton (1888), #58]Whoever interrupts the conversation of others to make a display of his own fund of knowledge, makes notorious his own stock of ignorance.
[tr. Ross (1900), #96]If any one interrupts the speech of others in order that people may know his stock of learning, they will discover the extent of his ignorance.
[tr. Platts (1904), #86]Those whose conversation has been interrupted by a man trying to show off his intelligence will know him instead by the depth of his ignorance.
[tr. Rehatsek/Newman (2004), #84]