After having described the state of affairs prevailing among hypocrites of distant deserts, it was considered appropriate that the true and staunch Muslims from among the same stock of Bedouins should also be mentioned. This was done in verse 99 - very much in line with the typical style of the Qur'an - so that, it stands established that Bedouins too are not all alike. Among them, there are many sincere Muslims, and people of sense and discernment as well. Their style of life is different. When they give in obligatory alms (Zakah) or in voluntary charities (Sadaqat), they regard these as a source of nearness to Allah Ta` ala and hope that the Holy Prophet ﷺ would be praying for them.
That Sadaqat are a source of nearness to Allah Ta` ala is obvious. However, the hope of prayers from the Holy Prophet ﷺ is on a different basis. It should be borne in mind that the Holy Qur'an - wherever it has asked the Holy Prophet ﷺ to collect Zakah on the wealth and property of Muslims - has also directed him that he should also pray for those who pay Zakah. The forthcoming verse (103): خُذْ مِنْ أَمْوَالِهِمْ صَدَقَةً تُطَهِّرُهُمْ وَتُزَكِّيهِم بِهَا وَصَلِّ عَلَيْهِمْ (Take out of their wealth a Sadaqah [ obligatory alms ] through which you may cleanse and purify them, and pray for them) is a good example? The instruction to the Holy Prophet ﷺ that he should pray for these people has been termed: وَصَلِّ عَلَيْهِمْ (and pray for them) using the word: صلٰوہ (salat) for it. Therefore, in the present verse as well, the sense of the prayers of the Holy Prophet ﷺ has been expressed by the use of the word: صلٰوہ (salat).