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48:29 Muhammad is the messenger of God, and those who are with him are stern against the concealers/rejecters/ingrates, but merciful between themselves. You see them inclining/humbling and SuJaD, seeking bounty from God and pleasure/approval. Their distinction is in their faces/attentions/considerations/wills/purposes, from the trace/teaching/influence of the SuJuD. Such is their example in the Torah. And their example in the Injeel is like a seed/crop which sends forth its shoot then strengthened it then becomes thick then stands upon its stem, pleasing to the sowers. That He may enrage the rejecters/concealers with them. God promises those who believe and do good works a forgiveness and a great reward.
It is interesting to note the preposition "fi" (in) not "ala" (on), making it "their distinction/mark is IN their faces/wills/purposes/considerations". Minority usage of "fi" can mean on/at however.
The word "athar" (root: Alif-Tha-Ra) basically means "that which is left behind from something" hence its meanings such as trace/mark/impression/teaching/influence and is not necessarily a physical thing, see 5:46, 18:6, 20:96, 30:50.
The word "seema" (root: Siin-Waw-Miim) means an identifying feature (e.g. could be the way someone looks or acts) see 2:273, 7:46, 7:48, 47:30, 55:41. Perhaps the majority of people would not have a trace of prostration on their face from physically prostrating in prayer for example, even if it was done many times per day, so this understanding, whilst superficially plausible, actually falls short. Some translators, e.g. Asad, do not take it to mean a physical mark on one's face.
It should be noted that "inclining and SJD" seems to relate to "seeking bounty from God and pleasure/approval" whose other occurrences relate to worldly benefits/provisions.
It should be noted that in the prior context, 48:25, it clearly implies some believers were unknown/unrecognisable, which makes it even more unlikely it is referring to a physical mark on one's face.
The "them" refers to the believers undergoing such growth. It may also imply that actualising oneself under the guidance of God's system leads to self-growth and benefits. There is an implication that the act of SJD can function as a catalyst to such growth, as it leaves an impression/influence upon such a person, thus the demeanor stems from that act/mindset, and results in fruitful growth and reward, and this is the message encapsulated in the example at the end. To achieve such effective growth, one's will/consideration/purpose/attention should be traceable back to the act of SJD.
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