The Meaning of Withholding Secrets
Kitman linguistically: is hiding. Istaktamahu sirrah (He did concealment of his secret through him) is used to mean one asking another to withhold his secret. Katamhu (with an alif) sirrah is also used.  al-Sihah, al-Jawhari (6/2329); Mukhtar al-Sihah, al-Razi (p. 266).
Kitman technically: is withholding speech. It is also said that it is controlling the self against the instigators of expressing that which perturbs it.  al-Mufradat, al-Raghib (p. 702); al-Akhlaq al-Islamiyyah, `Abd al-Rahman al-Maydani (2/343).
Sirr linguistically: is that which is hidden. Its plural is asrar. Sarirah holds the same meaning. A man who is sirri is secretive, does things secretly.  Lisan al-`Arab, Ibn Manzur (4/356); Taj al-`Arus, al-Zabidi (5/12).
Sirr technically: is speech withheld in the self.  al-Tawqif `ala Muhimmat al-Ta`arif, al-Manawi (p. 193). The Difference between Withholding, Secretiveness, Confidentiality (Najwa), and Hiding (Ikhtifa’)  al-Furuq al-Lughawiyyah, al-`Askari (p. 447-448, 533).
Confidentiality is secretive speech told to another in confidence. It is as if the one told is choicely elevated from others. Secretiveness is withholding matters within the self. If a matter is hidden behind a veil or a wall it is not considered a secret. One may say: ‘My secret is with so-and-so,’ meaning that which he withholds in himself. On the other hand, one does not say: ‘My confidentiality is with him.’ Withholding is associated with secrets and information - it is not used but with those meanings. Secretiveness is concerned with bodies and specific individuals. Withholding is being quiet with some meaning, whereas hiding is used for this meaning and others as well, so it is more general.Encouragement towards Withholding Secrets in the Qur’an and Sunnah
❖ Allah, exalted, says regarding Yusuf, peace be upon him, concealing his vision by the command of his father: “‘My son, tell your brothers nothing of this dream, or they may plot to harm you. Satan is man’s sworn enemy.’” Yusuf: 5. From this, it is understood that hiding blessings until they manifest is praiseworthy.  Tafsir Ibn Kathir (4/371).
❖ Mu`adh ibn Jabal, Allah be pleased with him, said: “Allah’s Messenger ﷺ said: ‘Seek aid to successfully accomplish your needs in discretion, for everyone who is blessed is also envied.”  Reported by al-Tabarani (20/94) (183) and al-Bayhaqi in Shu`ab al-Iman (6228). al-`Iraqi in Takhrij al-Ihya’ (1086). al-Haythami said in Majma` al-Zawa’id (8/198): “In its chain is Sa`id ibn Salam al-`Attar.” al-`Ijli said: “there is no problem with it, though Ahmad and others said it is false. The rest of its narrators are trustworthy, except that Khalid ibn Ma`dan did not hear from Mu`adh.” Quotes of the Predecessors and Scholars on Withholding Secrets
❖ `Ali ibn Talib, Allah be pleased with him, said: “Your secret is your prisoner, though as soon as you disclose it, you become its prisoner.”  Adab al-Dunya wa al-Din, al-Mawardi (p. 306).
❖ `Amr ibn al-`As, Allah be pleased with him, said: “I never placed my secret with anyone who disclosed it and I blamed him for that - It was I who constricted him when I confided in him with it.”  Reported by Ibn Abi al-Dunya in al-Samt (p. 214).
❖ al-Hasan, Allah have mercy upon him, said: “It is a form of treachery to disclose your brother’s secret.”  al-Samt wa Adab al-Lisan, Ibn Abi al-Dunya (p. 214). Benefits of Withholding Secrets  al-Ra’id Durus fi al-Tarbiyah wa al-Da`wah, Mazin al-Farih (p. 217).
Withholding secrets is a characteristic of decency and nobility. One of the greatest reasons to gain victory over enemies. It repels the corruption caused by envy and malice. Reaffirms brotherly ties. Increases trust between couples. Forms of Withholding Secrets
Hiding good deeds. Allah, exalted, says: “Call upon your Lord humbly and secretly.” al-A`raf: 55. Hiding sins. Abu Hurayrah, Allah be pleased with him, said: “The Messenger of Allah ﷺ said: ‘All of my Ummah will be fine, except those who are public in committing sin. A form of such heinous disclosure is that a person commits a sin at night and though Allah conceals it from the public, he comes in the morning and says: ‘So-and-so, I did such-and-such thing yesterday.’ He spent the night concealed by his Lord, then in the morning he removes Allah’s concealment from himself.’”  Reported by al-Bukhari (6069) and this is his wording, as well as Muslim (2990) from the narration of Abu Hurayrah, Allah be pleased with him. Concealing marital secrets. Allah’s Messenger ﷺ said: “Among those with the most evil stations in front of Allah on the Day of Resurrection are the man and his wife who confide secrets to one another then he discloses them.”  Reported by Muslim (1437) from the narration of Abu Sa`id al-Khudri, Allah be pleased with him. Hiding an evil dream. The Prophet ﷺ said: “... If a person sees other than that in his sleep, which he dislikes, then it is from the devil. He should seek refuge from its evil and not mention it to anyone, for it does not harm him.”  Reported by al-Bukhari (6985) from the narration of Abu Sa`id al-Khudri, Allah be pleased with him. Examples of Withholding Secrets from the Life of the Prophet ﷺ and Companions
❖ The Prophet ﷺ sent a brigade from the Emigrants assembled of twelve men, led by `Abdullah ibn Jahsh al-Asadi. He was carrying with him a message. The Messenger ﷺ commanded him that he not open it except after two days of travel. When he opens it and understands its content, then he should go about realising it without forcing any of those with him to do so with him.  Sirat Ibn Hisham (1/602).
❖ `Abdullah ibn `Umar narrated: “`Umar ibn al-Khattab said - when his daughter Hafsah lost her husband Khunays ibn Hudhafah al-Sahmi who was one of the companions of Allah’s Messenger ﷺ who fought in the battle of Badr and died in Madinah - he said: ‘I met `Uthman ibn `Affan and suggested that he should marry Hafsah saying: “If you wish, I will marry Hafsah bint `Umar to you.” On that, he said: “I will think it over.” I waited for a few days and then he said to me: “It is best if I do not marry at present.” Then, I met Abu Bakr and said: “If you wish, I will marry Hafsah bint `Umar to you.” He kept quiet and did not give me any reply. I became more angry with him than I was with `Uthman. Some days later, Allah’s Messenger ﷺ asked for her hand in marriage and I married her to him. Later on, Abu Bakr met me and said: “Perhaps you were angry with me when you offered me Hafsah for marriage and I gave you no reply?” I said: “Yes.” Abu Bakr said: “Nothing prevented me from accepting your offer except that I learnt that Allah’s Messenger ﷺ had mentioned his desire to marry her. I did not want to disclose the secret of Allah’s Messenger ﷺ. Had he given her up I would surely have accepted her.’”  Reported by al-Bukhari (4005).