I was looking for some specific inequalities concerning the absolute value, and I found this particular inequality in a question in this forum: Difference of powers inequality
The inequality is the following: $$ 2^{1-p}|x-y|^p\le\big|x|x|^{p-1}-y|y|^{p-1}\big|\le|x-y|(|x|^{p-1}+|y|^{p-1}), \text{ for }p\ge 1 $$ and $x,y \in \mathbb{R}$.
The user who posted this inequality as an answer named it "Mazur's inequality", but I was not able to find some references with that name on google. Are some of you familiar with this inequality? Can you provide a good reference/proof?