What is this flute inscription?
The full text is:

高適《塞上聽吹笛》
雪淨胡天牧馬還
月明羌笛戍樓間
借問梅花何處落
風吹一夜滿關山

Please note that the other proposed answer in the comments, apart from rendering the text in Simplified Chinese, also incorrectly identified the character「戍」as「戌」.