Making A Wasiyah Before Death

Zaid ibn Aslam reported that he narrated from his father, that his father said, ‘I remember a Hadith which was reported by Hazrat Umar Radi Allahu Anhu, that It is not permissible (i.e. advisable) for a Muslim to sleep three nights without placing his Wasiyah at his head-side, so I picked up a pen and ink so that I make write my Wasiyat.’  However, I kept all these (materials) at my head-side and fell asleep.  I saw a person appear to me in my dream, garbed in white robe and from his body emanated a sweet fragrance.  I asked, ‘Sir who permitted you to enter my home?’  He said, ‘the people of the house.’  I asked, ‘Who are you?’  He said, ‘Malak ul Maut’.  On hearing this, I began to pull away from him.  He said, ‘Do not try to avoid me.’  I have not come to remove your soul.  I said to him, ‘Write for me a certificate of security from the fire of hell.’  He said, ‘Hand me the pen and ink’, so I handed him the pen, ink and paper which was kept at my head-side, so he wrote:

بسم الله الرحمن الرحيم , أستغفر الله , أستغفر الله

BISMILLAAHIRRAHMAANIRRAHEEM, ASTAGHFIRULLAH, ASTAGHFIRULLAH

He filled both ends of the paper with these words (i.e. he wrote this on the entire sheet of paper), and then handed the paper over to me saying, this is your Certificate of Salvation.  I awoke (from my dream) in a state of shock.  I then asked for a candle to be brought and looked at that paper which I had kept at my head-side.  I found the exact words written on that page. 

[Sharh us Sudoor Bi Sharhi Haalil Mauta Wal Quboor]