The Quran

Preface

لا تَجعَلوا دُعاءَ الرَّسولِ بَينَكُم كَدُعاءِ بَعضِكُم بَعضًا ۚ قَد يَعلَمُ اللَّهُ الَّذينَ يَتَسَلَّلونَ مِنكُم لِواذًا ۚ فَليَحذَرِ الَّذينَ يُخالِفونَ عَن أَمرِهِ أَن تُصيبَهُم فِتنَةٌ أَو يُصيبَهُم عَذابٌ أَليمٌ

Yusuf Ali

Deem not the summons of the Messenger among yourselves like the summons of one¹ of you to another: God doth know those of you who slip away under shelter of some excuse: then let those beware who withstand the Messenger’s order, lest some trial befall them,² or a grievous penalty be inflicted on them.

Three significations are possible. One is that adopted in the Translation, which agrees with the view of most Commentators. Another would be: 'Do not think that the prayer of the Prophet of God is like your ordinary requests to another: the Prophet’s prayer will be about serious matters and will be accepted by God.' A third interpretation would be: 'Do not address the Prophet familiarly as you would address one another: use proper terms of respect for him.'
The “trial” is understood to be some misfortune in this life, and the “grievous Penalty” to be the punishment in the Hereafter.