Kretchnif (also written as Kretchinev, Kretchniv, Kretshniff) is a Hasidic Jewish dynasty that comes from the Nadvorna dynasty.
Grand Rabbi Avraham Abba Leifer, previous Pittsburgher Rebbe, a scion of the Nadvorna dynastyNadvorna is a Hasidic rabbinical dynasty within Orthodox Judaism. The dynasty derives its name from the town of Nadvorna, now known as Nadvirna, Ukraine. The town was located in Poland between the two world wars, and was in the province of East Galicia in the Austro-Hungarian Empire until World War I. The most famous rebbe of the dynasty was Rabbi Mordechai Leifer of Nadvorna (the son of Rabbi Yisachar Ber “Bertchi” Leifer of Nadvorna). He was raised by his great-uncle, the Rebbe Meir the Second of Premishlan. He was well known as godly man, and Hasidim from all over Hungary and Romania would come to receive his blessings and his advice, he was also known as a great miracle worker. His teachings are collected in Gedulas Mordechai, Tiferes Mordechai, Aspaklarya Hameira, and Maamar Mordechai Oros Mordechai.
Rabbi Yisachar Ber “Bertchi” Leifer of Nadvorna was a son of Rabbi Yitzchak of Kalish (a brother of Rabbi Meir of Premishlan), A son of Rabbi Aharon Leib Of Premishlan, A son of Rabbi Meir Hagadol of Premishlan. The Nadvorna Dynasty is famous inasmuch as many of its descendants become Rebbes. It has perhaps the largest numbers of rebbes of any Hasidic dynasty. Since many of the rebbes of the Nadvorna Dynasty (as in other rabbinic dynasties) married relatives, many of the rebbes in this list are sons-in-law of other rebbes on the list.
One famous custom of the rebbes of the Nadvorna Dynasty is to play a violin on special occasions, for instance in front of the menorah on the festival of Hannukah.
Grand rabbis are known as “Admorim” (Hebrew which is the acronym for “Adonainu Morainu V’Rabainu”, “Our master, Our teacher, and Our Rabbi”). Text from Wikipedia