It wasnarrated from Sa'd bin Abu Waqqas that the Messenger of Allah(ﷺ)said:
'Weep, and if you cannot weep then pretend to weep." (RU)
English reference (RU): Vol. 5, Book 37, Hadith 4196 (RU)
Arabic reference (RU): Book 37, Hadith 4336 (RU)