Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated from the Messenger of Allah (peace and blessings be upon him), he (peace be upon him) said: "When a gift is given to any one of you and there are some people present with him, then they also share in it."
Hadith Referenceمسند اسحاق بن راهويه / كتاب الهبة و فضلها / 503