Humayd said that Bakr bin Abdullah (may Allah have mercy on him) used to say: One should write: "In the name of Allah, the Most Gracious, the Most Merciful. To so-and-so son of so-and-so," and one should not write: "For so-and-so son of so-and-so."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب آداب القاضي / 20429