同病相怜

tóngbìng-xiānglián

[fellow sufferers have mutual sympathy; those who have the same illness sympathize with each other; adversity makes strange bedfellows; company in distress makes trouble less; fellow sufferers commiserate with each other] 比喻因遭遇同样的不幸而共相怜恤

同病相怜, 同忧相救。 --《吴越春秋》