R. Avraham Klatzkin was the son of R. Naftali Hirtz Klatzkin, a chossid of the Tzemach Tzedek who was a famous gaon and the Rov of Shimberg, Latvia. R. Avraham served as the Rov of Romanov, and then Liozna. After the Tzemach Tzedek's passing he became a chossid of the Chabad Rebbes of Liadi, as his father was. He eventually became a chossid of the Rebbe Rashab and corresponded with him on matters of halacha.
R. Avraham was a well-known Rov in his time, and talmidim of Tomchei Temimim in Lubavitch would visit him to receive semichah. Some of his chidushim are published in Amudei Sheish, and comments he wrote in the margins of his seforim have been published in various journals.
R. Avrohom was an exceptional masmid. He didn't have anyone with whom to share his Torah insights, yet he would rise in middle of the winter night and learn for hours while standing.
Once, the Rebbe Rashab spoke in a maamar about the importance of studying Torah lishma, for its own sake, and not for any ulterior motive. Afterwards, R. Shmuel Levitin, who was then a tomim in Lubavitch, commented to his fellow tomim, R. Hirshel Gurary, "The Rebbe isn't speaking to us since we don’t learn perfectly anyway. He's refering to the rov Klatzkin."
(ניצוצי אור - וויינגארטן)
Passing by his son who sat learning Gemara to a tune, R. Avrohom severely admonished the boy. R. Avrohom's brother expressed his wonder, since the boy had been learning well. R. Avrohom explained that from the boy's tune of learning he could sense that it wasn't lishma, but rather to pride himself with his knowledge.
R. Avrohom is described as having an incredible anticipation for Moshiach, which put him in good spirits. He would sleep half dressed in his clothing so that he would be able to quickly run to greet Moshiach.
As a result of his bitachon he was unfazed by his poverty, and to worry about tomorrow seemed to him foolish and heretical.
(היכל הבעש"ט ח"מ ע' רצב ואילך)
