It wasnarrated from Abu Hurairah that the Prophet (ﷺ) said:
"Whoevercatches one Rak'ah of Friday, let him add another Rak'ah toit." (RU)
English reference (RU): Vol. 1, Book 5, Hadith 1121 (RU)
Arabic reference (RU): Book 5, Hadith 1175 (RU)