Showing Proper Respect for Sefarim
There is an entire section in Shulchan Aruch dedicated to the halachos of kevod sefarim, showing proper respect for sefarim: According to halachah, one may not sit on a desk, bed, or bench on which there is a sefer; the sefer should be elevated at least a tefach (a handbreadth), although some poskim say it is pious behavior to elevate it more. In case there is no other place to sit, it is permissible to sit there. One should not put a sefer on their knees and lean their elbows on it. Objects (glasses, cellphones etc.) should not be placed on top of seforim. Sefer Chassidim mentions a number of pious behaviors in regards to sefarim: If a person is carrying sefarim, they should not say, “Kamah tarachti!” (“How difficult it was to carry those sefarim!”) If a person is buying a sefer, they should not say, “Ra, ra!” (“The price is ridiculously high!). Rather, they should say, “I am only able to pay such and such an amount, and I am not prepared to pay more,” but they should not complain that the price is too high. One should not have a drink over an open sefer, as it might spill and damage the sefer. However, if one is extra-cautious, doing so is permissible. #284?1
1 ראה שו״ע יו״ד סרפ״ב ס״ז. ובש״ך שם. וראה ספר חסידים סקנ״ז. תתצא. תתקכה. וראה בכ״ז בהנסמן בס׳ הספר בהלכה. בס׳ גנזי הקודש. ועוד. וקחנו משם.