that the Messenger of Allah ﷺ said: "From the complete of visiting the ill is that one of you place his hand on his forehead" - or he said - "on his hand, and ask him how he is. And shaking hands completes your greetings among each other." (Using translation from Tirmidhī 2731)
عَنِ النَّبِيِّ ﷺ قَالَ مِنْ تَمَامِ عِيَادَةِ الْمَرِيضِ أَنْ يَضَعَ أَحَدُكُمْ يَدَهُ عَلَى جَبْهَتِهِ أَوْ يَدِهِ فَيَسْأَلُهُ كَيْفَ هُوَ؟وَتَمَامُ تَحِيَّاتِكُمْ بَيْنَكُمُ الْمُصَافَحَةُ