Lewis & Short

exhortātĭo, ōnis, f. [exhortor], an exhorting, exhortation, encouraging (mostly post-Aug.; not in Cic.): quae tua exhortatione excepi, Planc. ap. Cic. Fam. 10, 7, 1; Quint. 12, 2, 6: strepere cuncta clamoribus et tumultu et exhortatione mutua, Tac. H. 1, 36; Vulg. Act. 13, 15 al. et saep.
In plur., Quint. 10, 1, 47; Col. 11, 1, 17; Just. 38, 3 fin.
With obj. gen.: studiorum, Quint. 12, 11, 25.