R’ Ezriel Zelig Slonim of Yerushalayim related:

In 1929, after hearing that the Frierdiker Rebbe had left Soviet Russia, I resolved to spend Shavuos with him. Since Latvia required an official invitation from a local resident in order to obtain a visa, I traveled to Berlin to arrange the necessary documents.

Upon arriving in Berlin, I made my way to the home where the Rebbe, then the future son-in-law of the Frierdiker Rebbe, was staying. The family hosting the Rebbe informed me that he was fasting that day, something they said he did often.

When I knocked on the door to his room, I found the Rebbe wearing Rabbeinu Tam tefillin and learning Talmud Yerushalmi. He motioned for me to sit down and wait until he finished learning. After removing the tefillin, he rose from his place and warmly extended his hand to greet me.

When I explained the reason for my visit, the Rebbe immediately accompanied me to the post office, where we sent a telegram to the Frierdiker Rebbe in Riga requesting that an official invitation be issued in my name.

When we went out to the street, I noticed that the Rebbe was wearing gloves on his hands, protecting his hands from anything impure.

(Eved Melech, pp. 123–124)