My father is looking for an old friend of his.

我的父亲正在寻找他的一位老朋友。

youdao

The grey-haired diplomat came across an old friend, which reminded him of the youthful days when struggling for their ideals.

一位白发苍苍的外交官与老友不期而遇，脑海中回想起了为理想而奋斗的青春时光。

youdao

I met an old friend from whom I had parted for many years.

我见到了分离多年的朋友。

《新英汉大辞典》

Gardner was caught after agreeing to collect three parcels from a courier as a favour for an old friend.

BBC: Four major drug dealers jailed after police raids

It amounted, in short, to a rescue for an old friend.

ECONOMIST: Gambling with the mighty greenback | The

He had visitors for lunch, an old Civil Service friend, a retired State Bank governor, and his cousin the retired General Karim, along with their wives.

NEWYORKER: In Other Rooms, Other Wonders