How sound is what was narrated from Ibn Umar concerning supplications and acts that are recited and performed upon losing something, and is it legislated to act upon them?

The aforementioned Hadith is weak due to the ignorance of one of its narrators. However, there is no harm in acting upon it, for prayer is legislated. The Prophet, peace and blessings be upon him, whenever he was troubled by an affair, would resort to prayer. And there is no harm for a person to supplicate for his need during his prayer.