salaam why it was written ALLAH subhana talla knows best but it is amazing how ala Hazret wrote this hamd and he was saying that; wahi rabb hai jis ne tuj ko hama tan karam banya hmien bheek mangne ko tera aastaana bataaya tuje haam hai kudaaya as you said he included in it the naat telling us that RasuALLAH sallahu 'alahi wasallam is compassionate and is mercy for all and may ALLAH subhana tala grant us his mercy and we get to drink from the kuwad al kuwthir ameen. It shows us the love that ala Hazret has for RasuALLAH sallahu 'alahi wasallam that he mentioned the LOVED and Beloved together ALLAH HU AKBER. Whether ala Hazret was told to write tha hamd or not he still mentioned the Beloved and that's what you truly call love. I'm not sure if that's the answer you were looking for but ALHAMDULILLAH.
he wrote a hamd/na'at: wahi rabb hai jis ne tujh ko hama tan karam banaaya did he write this of his own accord or did someone ask him? i read somewhere that someone asked him to write a hamd but because alaHazrat always wrote in praise of rasulAllah sallAllahu 'alaihi wasallam too; he wrote the hamd and also included the na'at within. it is majestic. the rank of rasulAllah sallAllahu 'alaihi wasallam [na'at] is attributed to the granting of Allah [hamd] thus: wahi rabb hai jis ne tujh ko hama tan karam banaaya hameiN bheek maangne ko tera aastaaN bataaya tujhe Hamd hai khudaaya Our Lord is He who has made you an embodiment of Compassion; Who has commanded us to seek pardon through your intercession. Praise be to Allah from the entire creation.
