«نَفْخِةْ إِصْطَبْلْ»

The image comes from a horse or other mount that has stood in its stall, eating its fill and resting. When led out, it prances and seems spirited, but that liveliness is only a swelling of comfort, not breath or boasting. Once someone rides and works it, the show of strength quickly drains away.

Applied to people, the saying marks someone whose ease and good living make them look capable, energetic, or ready for hard tasks. The speaker suggests that this impression is hollow and that, once real effort is required, the person will tire and their lack of substance will show.

Use it skeptically, not admiringly, about someone whose vigor seems to come from ease rather than proven ability, such as an untested newcomer. Said directly to that person, it can sound belittling, since it predicts the energy will fade under real demands.