Mukashifatul Qulub to what I gather has been translated into English, but I doubt Akhlaq Us-Salikeen is translated.
It is stated in Mukashifatul Qulub: Sayyiduna Ataa al-Khurasani radi Allahu anhu reports that the Beloved Messenger of Allah şallAllāhu álayhi wa sallam passed by a group of people who were laughing aloud. The Beloved Messenger of Allah şallAllāhu álayhi wa sallam said, Remember that which destroys the taste of pleasures. He was asked, O Master şallAllāhu álayhi wa sallam, what is that? The Beloved Prophet şallAllāhu álayhi wa sallam replied: Death
Sayyiduna Hasan Basri radiyahallhu ta'ala anhu saw that a person was laughing and asked him, ‘Oh young man! Have you crossed the bridge of Siraat yet?’ He replied no. He was then asked. ‘Do you know whether you will go to Heaven or Hell?’ He again replied in the negative. He radiyahallhu ta'ala anhu said, ‘Then why this laughter? You should not be laughing when you are aware of the difficulties ahead of you and you are unaware of your final destination.’ From that time on, this young man was never seen to laugh again.[1] ________________________________ [1] Akhlaq Us Saliheen, Pg 44, Maktaba Tul Madina, Baab Ul Madina, Karachi