What is appropriate is that anyone who wishes to revive the sunnah—whether in this matter or in any other that the people have neglected or altered, provided it does not undermine the foundations of Islam—should first weigh the consequences. If acting on it, or leaving it aside, is likely to stir up turmoil and harm outweighing its benefit, he must take the overall interest into account, for the Sacred Law follows pure benefit or that whose benefit clearly predominates over harm.

Hadith Thirteen
Abū Qatadah al-Anṣārī (may Allah be pleased with him) reported: The Messenger of Allah ﷺ used to pray while carrying Ummāmah, the daughter of Zaynab, daughter of the Messenger of Allah ﷺ, whose father was Abū al-ʿĀṣ ibn al-Rabīʿ ibn ʿAbd Shams. When he went into prostration he would place her on the ground, and when he stood he would pick her up again.

Overall meaning
The Prophet ﷺ was the epitome of kindness, gentleness, compassion, and mercy, endearing himself to young and old, rich and poor alike. A vivid proof of his noble character is that he carried one of his granddaughters during prayer: he would rest her on his shoulder when standing, and set her down whenever he bowed or prostrated. In this gracious concession lies a ruling that makes worship easier for the Muhammadan community.

Scholarly disagreement
Ibn Daqīq al-ʿĪd, in his commentary on this book, advanced numerous far-fetched interpretations of this hadith—claims of abrogation, exclusivity, necessity, and other explanations even weaker and less persuasive.

Al-Qurṭubī remarked, “The scholars have differed in interpreting this hadith; what compelled them to do so is that it involves a considerable amount of movement.”

After reviewing these interpretations, al-Nawawī said, “All such claims are baseless and must be rejected, for there is no evidence to support them.” It has therefore become clear, according to the verifying scholars, that this kind of slight movement is permissible in every prayer—obligatory or voluntary—for the imam, the follower, and the individual alike, and that the Prophet ﷺ did it solely to demonstrate its permissibility.