Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrated this as a marfu' hadith (attributed to the Prophet): The Prophet (peace and blessings be upon him) said: "Allah Almighty spoke to the western sea and spoke to the eastern sea. He said to the western sea: 'I will make some of My servants ride upon you; what will you do with them?' It replied: 'I will drown them.' So Allah Almighty said: 'Your harm will be in your surrounding regions,' and Allah Almighty deprived it of ornaments and game. Then Allah Almighty spoke to the eastern sea and said: 'I will make some of My servants ride upon you; what will you do with them?' It replied: 'I will carry them upon my body, and I will be for them as a mother is for her children.' So Allah Almighty rewarded it with ornaments and game."
Al-Bazzar recorded it as a wijadah (a narration taken from a written source). Its chain contains a narrator, Abd al-Rahman bin Abdullah bin Umar al-Umari, who is matruk (abandoned).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الجهاد / 9451