It’s the last letter preserved (by his Mother, Maria Kolbe) that came from his hand:
“My dearest Mom,
Towards the end of the month of May I reached the concentration camp of Auschwitz (Oswiecim) by rail convoy.
Everything is going well with me. Beloved Mom, don’t worry about me or about my health, because the good God is everywhere and with immense love he thinks about all of us and about everything. It would be best not to write to me u nil I send you another letter. I don’t know how long I shall remain here.
with heartfelt Greetings and a Kiss.”