Imam Abu 'Abdillah Muhammad b. Marzuq al-'Ayyashi (may Allah have mercy upon him) was asked if it is proper to send prayers upon the Prophet (Allah bless him and give him peace) while walking through the marketplace. He replied: "This practice is 'against what is superior' [khilaf al-awla]."
The questioner then asked him, "If that is so, then why have we been encouraged to remember Allah in the marketplaces—as is mentioned in a number of hadith traditions?" The Shaykh replied,
"It is because our prayers upon the Messenger of Allah (Allah bless him and give him peace) are presented to him in their exact form, including the time and place in which they were uttered, so it behooves the invoker of prayers to actively seek out a wholesome, pure, and clean place for them."
(Shaykh Muhammad Tahir al-Kattani, Matali' al-Sa'ada fi Iqtiran Kalimatay al-Shahada, pp. 239–240)
اللَّهُمَّ صَل عَلَى سَيِّدِنَا مُحَمَّدٍ ۞ الفَاتِحِ لِمَا أُغْلِقَ ۞ وَالخَاتِمِ لِمَا سَبَقَ ۞ نَاصِرِ الحَقِّ بِالحَقِّ ۞ وَالهَادِي إِلَى صِرَاطِكَ المُسْتَقِيمِ ۞ وَعَلَى آلِهِ حَقَّ قَدْرِهِ وَمِقْدَارِهِ العَظِيمِ ۩
Allaahuve muth nabiye mun nirthi dua cheyyukayaanu..ennem muthuvinem ennum opparaakkane..njangale piriyippikkalle..avan nte maathram aakane..jeevithatthilum maranatthilum maranathin sheshom njangal opparaavane.onnaakane..avale iyy best doctor aakkane..oolde per kelkkumpozhekk alkkare rogam maaranee
Ella nimishavum muth nabiye unarvil thanne kaanaan ulla baagyam njagalkk nalkane
Njangalkk nee ninne thanne nalkane
Aameen bi jahi nabiyyil ameen sallallahu alaihi wasallam