How Authentic Is Bhai Bala's Janam Sakhi

[Anad 5]

Hello everyone.

I recently came across a question posted by someone on Quora. The question had a verse from Bhai Bala's Janam Sakhi ( I have'nt verified if the verse exists there), which supposedly was said by Guru Nanak Dev Jee ( does not seem true to me though).

The verse was ":

“Pakh Padho Kalma Rab da Muhammad nal Milay.
“Ho Ya Mashuk-e-Khuda yeda ho ya Yallah”

(Bhai Bhala’s Janam Sakhi p.14)

Recite the Kalma of the Creator adding to it the name of Muhammad.
Who is the beloved of God by dedication of his very self to Allah. (I strongly doubt that Guru Jee must have said this :-( )

The person who posted the question was asking, if Guru Jee said this then why do we not consider Their Prophet as a messenger from God???

Obviously this cannot be true. If Guru Jee wanted us to read the kalma, then why would he have composed the Mool mantra, the Japji???

Well, maybe if at all, it was uttered by Him, which I doubt, then it must have been an advice to the muslims...maybe.

What do you all think about this? I want to answer this question,but I am doubtful about where this verse comes from.