赠人玫瑰手无余香
[zèng rén méi guī shŏu wú yú xiāng]
Literally it means 'when you send someone a rose, the fragrance doesn't stay on your hands'. However, contrary to the common idiom 'Gifts roses, hand remains fragrant' that emphasizes doing something good for others can benefit yourself as well, the author may want to express the idea that he has no harvest in spite of being helpful to other people.