“Bulgarian the early season of its evangelization had been taught that no work should be performed on the Sabbath.” Responsa Nicolai Papae I and Con-Consulta Bulllllgarorum, Responsum 10, found in Mansi, Sacrorum Concilorum Nova et Amplissima Colectio, Vol.15; p. 406; also Hefele, Conciliengeschicte, Vol.4, sec. 478
(Pope Nicholas I, in answer to letter from Bogaris, ruling prince of Bulgaria.) “Ques. 6-Bathing is allowed on Sunday. Ques. 10-One is to cease from work on Sunday, but not also on the Sabbath.” Hefele, 4,346-352, sec. 478 The Bulgarians had been accustomed to rest on the Sabbath. Pope Nicholas writes against this practice.
“Pope Nicholas I, in the ninth century, sent the ruling prince of Bulgaria a long document saying in it that one is to cease from work on Sunday, but not on the Sabbath. The head of the Greek Church, offended at the interference of the Papacy, declared the Pope ex-communicated.”