I took money from my boss

My boss asked me to buy him something that I didn’t have any interest in but he asked for so I bought it for him. He then asked me for money because he wanted to get something else. I told him no and I didn’t have any. He said he had 40 bucks but it was 4 dollars and I didn’t want to pay that. I gave him the 40 and I didn’t tell my mom. I don’t want her to know and I feel terrible.