Salaam.
Prayer is a general word. Prayer may be formal or informal. In my last post it is prayer in my (borrowed) translation of 5:106.
The reason why it is not necessarily the formal, prescribed, time bound Salat, but only "sheer paying rapt attention to God", (please read my previous post) is that in the Arabic text, the word Salah is written without the letter waw in 5:106 as well as in 29:45, and also in many other places.
Such differences in the construction of the word Salah in different places in the Quran and their vital significance has been pointed out by Muhammed Shahrur in "Qur'an, Morals and Critical Reason", available in the Net.
Regards,
A. Ismail Sait.